ABCB3 p.Lys509Met
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PMID: 12501238
[PubMed]
Lapinski PE et al: "Nucleotide interactions with membrane-bound transporter associated with antigen processing proteins."
No.
Sentence
Comment
46
EXPERIMENTAL PROCEDURES Baculoviruses for Expression of TAP1, TAP2, TAP1(K544M), TAP2(K509M), T2MT1C, T1MT2C, TAP1-eGFP, and TAP2-eYFP- Baculoviruses encoding wild type human TAP1 and TAP2 were obtained from the laboratory of Dr. Robert Tampe´ (22).
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ABCB3 p.Lys509Met 12501238:46:86
status: NEWX
ABCB3 p.Lys509Met 12501238:46:127
status: NEW47 We have previously described the construction of baculoviruses encoding the TAP1 mutant (TAP1(K544M) and the TAP2 mutant (TAP2(K509M)) (5).
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ABCB3 p.Lys509Met 12501238:47:127
status: NEW99 Mutation of the TAP2 Walker A lysine residue (TAP2(K509M)) reduced the TAP2-associated signal and derived affinity (KD Ͼ 20 M when expressed in complex with TAP1-eGFP) (Fig. 2, E, bottom panel compared with top panel, and H and Table I).
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ABCB3 p.Lys509Met 12501238:99:51
status: NEW116 In the corresponding TAP1-eGFP/TAP2(K509M) complexes, a similar affinity was derived corresponding to TAP1-eGFP labeling (KD ϭ 2.8 Ϯ 2.9 M) (Fig. 2I and Table I).
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ABCB3 p.Lys509Met 12501238:116:36
status: NEW118 However, the signals derived for TAP1-eGFP in the TAP1-eGFP/TAP2(K509M) mutant complex are reduced compared with that derived for the wild type complex (Fig. 2I), even though slightly higher levels of TAP1-eGFP were present in the mutant complex (Fig. 2C, lane 1 compared with lane 2).
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ABCB3 p.Lys509Met 12501238:118:65
status: NEW124 Insect cell microsomal membranes expressing TAP1 alone or TAP2-eYFP alone (A), the TAP1-eGFP/TAP2 or TAP1-eGFP/TAP2(K509M) combinations with the TAP1-eGFP component in excess (B), or the TAP1-eGFP/TAP2 or TAP1-eGFP/TAP2(K509M) combinations with the TAP2 or TAP2(K509M) components in excess (C) were incubated with different concentration of 8-azido-[␥-32 P]ATP for 15 min on ice and subsequently cross-linked by UV irradiation.
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ABCB3 p.Lys509Met 12501238:124:116
status: NEWX
ABCB3 p.Lys509Met 12501238:124:220
status: NEWX
ABCB3 p.Lys509Met 12501238:124:262
status: NEW133 Mutation of the TAP2 Walker A lysine TAP2(K509M) reduced TAP2 labeling and the corresponding affinity.
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ABCB3 p.Lys509Met 12501238:133:42
status: NEW135 The binding affinity corresponding to TAP1-eGFP labeling when in complex with wild type TAP2 is similar to that derived when TAP1 is in complex with the nucleotide binding-deficient TAP2(K509M).
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ABCB3 p.Lys509Met 12501238:135:187
status: NEW137 KD (ATP) n KD (ADP) n M M TAP2 nucleotide binding TAP2-eYFP 19.3 Ϯ 2.5 2 4.4 Ϯ 1.4 2 TAP2/TAP1-eGFP 2.7 Ϯ 1.0 3 0.5 Ϯ 0.1 2 TAP2(K509M)/TAP1-eGFP Ͼ20 4 9.0 Ϯ 1.4 2 TAP1 nucleotide binding TAP1 4.6 Ϯ 1.9 3 1.4 Ϯ 0.1 2 TAP1-eGFP/TAP2 2.1 Ϯ 0.8 3 0.7 Ϯ 0.1 3 TAP1-eGFP/TAP2(K509M) 2.8 Ϯ 2.9 4 0.6 Ϯ 0.2 3 The data shown in Fig. 2 were derived from analyses of 8-azido-[␥-32 P]ATP binding to TAP1/TAP2 complexes.
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ABCB3 p.Lys509Met 12501238:137:169
status: NEWX
ABCB3 p.Lys509Met 12501238:137:347
status: NEW161 For these analyses, we prepared microsomes containing TAP1(K544M)/ TAP2 complexes and TAP1(K544M)/TAP2(K509M) complexes.
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ABCB3 p.Lys509Met 12501238:161:103
status: NEW163 At comparable expression levels of both components (Fig. 4D), strong labeling was visualized for the TAP1(K544M)/TAP2 combination, whereas signals for the TAP1(K544M)/TAP2(K509M) combination were barely detectable (Fig. 4E, top and middle panels, respectively).
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ABCB3 p.Lys509Met 12501238:163:172
status: NEW173 eYFP complexes (Fig. 4E, bottom panel), a corresponding distinct signal was not visualized in the TAP1(K544M)/ TAP2(K509M) combination (Fig. 4E, middle panel), despite the higher expression of TAP1(K544M) in the latter complexes.
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ABCB3 p.Lys509Met 12501238:173:116
status: NEW184 Using TAP1-eGFP/TAP2(K509M) complexes under conditions of TAP1 excess or TAP2 excess (Fig. 2), we determined that the two nucleotide-binding sites of TAP1/TAP2 complexes did in fact bind 8-azido-ATP with apparent affinities that were, within the error of these measurements, quite similar to each other.
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ABCB3 p.Lys509Met 12501238:184:21
status: NEW199 E, phosphorimaging analyses of 8-azido-[␥-32 P]ATP binding to microsomes containing TAP1(K544M)/TAP2 (top panel), TAP1(K544M)/TAP2(K509M) (middle panel), or TAP1(K544M)/TAP2-eYFP (bottom panel).
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ABCB3 p.Lys509Met 12501238:199:138
status: NEW200 Signals corresponding to TAP1 (K544M) could be observed when in complex with TAP2-eYFP but not when in complex with TAP2(K509M).
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ABCB3 p.Lys509Met 12501238:200:121
status: NEWX
ABCB3 p.Lys509Met 12501238:200:137
status: NEW201 The absence of a signal was not due to the expression level, as TAP1(K544M) was expressed at higher levels in the microsomes with the TAP2(K509M) combination compared with the TAP2-eYFP combination (see D).
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ABCB3 p.Lys509Met 12501238:201:121
status: NEWX
ABCB3 p.Lys509Met 12501238:201:139
status: NEW209 Mutation of the TAP2 Walker A lysine residue (TAP2(K509M)) indeed influenced nucleotide binding at the TAP2 site (Fig. 2).
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ABCB3 p.Lys509Met 12501238:209:51
status: NEW214 However, co-expression of TAP1(K544M) with TAP2(K509M) resulted in a nucleotide-binding deficient complex (Ref. 7 and Fig. 4).
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ABCB3 p.Lys509Met 12501238:214:48
status: NEW216 What mechanisms could be responsible for enhanced TAP1 labeling in TAP1(K544M)/TAP2-eYFP complexes compared with TAP1(K544M)/TAP2(K509M) complexes?
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ABCB3 p.Lys509Met 12501238:216:130
status: NEW221 When we compared 8-azido-[␥-32 P]ATP binding by TAP1-eGFP in TAP1-eGFP/TAP2 complexes and TAP1-eGFP/ TAP2(K509M) complexes, we found that the TAP1-eGFP labeling intensity was enhanced when in complex with wild type TAP2 compared with TAP2(K509M).
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ABCB3 p.Lys509Met 12501238:221:113
status: NEWX
ABCB3 p.Lys509Met 12501238:221:246
status: NEW224 We observed that the derived affinity corresponding to TAP1(K544M) labeling in TAP1(K544M)/TAP2-eYFP complexes was nearly identical to that corresponding to TAP2-eYFP labeling (Fig. 4C) and significantly higher than that measured in TAP1(K544M)/TAP2(K509M) (Fig. 4E, middle panel; KD cannot be estimated because significant labeling was not visualized).
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ABCB3 p.Lys509Met 12501238:224:250
status: NEW225 Thus, the TAP2(K509M) mutation appears to have distinct effects on labeling of TAP1 compared with TAP1(K544M).
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ABCB3 p.Lys509Met 12501238:225:15
status: NEWX
ABCB3 p.Lys509Met 12501238:225:250
status: NEW237 High affinity labeling of TAP1(K544M) residues in TAP1(K544M)/TAP2-eYFP complexes (Fig. 4), but not of TAP2(K509M) residues in TAP1-eGFP/TAP2(K509M) complexes (Fig. 2), might arise because of conformational differences between the two mutant complexes.
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ABCB3 p.Lys509Met 12501238:237:108
status: NEWX
ABCB3 p.Lys509Met 12501238:237:142
status: NEW250 The analyses undertaken here also allow for a reassessment of the effects of TAP1(K544M) and TAP2(K509M) mutations upon peptide binding to TAP1/TAP2 complexes.
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ABCB3 p.Lys509Met 12501238:250:98
status: NEW252 Both mutant complexes were found to bind TAP-specific peptides with high affinity at room temperature (5); however, whereas the binding affinity of the TAP1(K544M)/TAP2 complex (KD ϭ 17.4 Ϯ 4.8 nM) was very similar to wild type (KD ϭ 19.4 Ϯ 4.8 nM), the affinity of the TAP1/TAP2(K509M) was ϳ2-fold reduced (KD ϭ 39.2 Ϯ 5.9 nM).
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ABCB3 p.Lys509Met 12501238:252:304
status: NEW45 EXPERIMENTAL PROCEDURES Baculoviruses for Expression of TAP1, TAP2, TAP1(K544M), TAP2(K509M), T2MT1C, T1MT2C, TAP1-eGFP, and TAP2-eYFP- Baculoviruses encoding wild type human TAP1 and TAP2 were obtained from the laboratory of Dr. Robert Tampe &#b4; (22).
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ABCB3 p.Lys509Met 12501238:45:86
status: NEW98 Mutation of the TAP2 Walker A lysine residue (TAP2(K509M)) reduced the TAP2-associated signal and derived affinity (KD b0e; 20 òe;M when expressed in complex with TAP1-eGFP) (Fig. 2, E, bottom panel compared with top panel, and H and Table I).
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ABCB3 p.Lys509Met 12501238:98:51
status: NEW134 Mutation of the TAP2 Walker A lysine TAP2(K509M) reduced TAP2 labeling and the corresponding affinity.
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ABCB3 p.Lys509Met 12501238:134:42
status: NEW136 The binding affinity corresponding to TAP1-eGFP labeling when in complex with wild type TAP2 is similar to that derived when TAP1 is in complex with the nucleotide binding-deficient TAP2(K509M).
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ABCB3 p.Lys509Met 12501238:136:187
status: NEW138 KD (ATP) n KD (ADP) n òe;M òe;M TAP2 nucleotide binding TAP2-eYFP 19.3 afe; 2.5 2 4.4 afe; 1.4 2 TAP2/TAP1-eGFP 2.7 afe; 1.0 3 0.5 afe; 0.1 2 TAP2(K509M)/TAP1-eGFP b0e;20 4 9.0 afe; 1.4 2 TAP1 nucleotide binding TAP1 4.6 afe; 1.9 3 1.4 afe; 0.1 2 TAP1-eGFP/TAP2 2.1 afe; 0.8 3 0.7 afe; 0.1 3 TAP1-eGFP/TAP2(K509M) 2.8 afe; 2.9 4 0.6 afe; 0.2 3 Nucleotide Binding by the TAP1/TAP2 Complex The data shown in Fig. 2 were derived from analyses of 8-azido-[ॹ-32 P]ATP binding to TAP1/TAP2 complexes.
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ABCB3 p.Lys509Met 12501238:138:167
status: NEWX
ABCB3 p.Lys509Met 12501238:138:345
status: NEW162 For these analyses, we prepared microsomes containing TAP1(K544M)/ TAP2 complexes and TAP1(K544M)/TAP2(K509M) complexes.
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ABCB3 p.Lys509Met 12501238:162:103
status: NEW164 At comparable expression levels of both components (Fig. 4D), strong labeling was visualized for the TAP1(K544M)/TAP2 combination, whereas signals for the TAP1(K544M)/TAP2(K509M) combination were barely detectable (Fig. 4E, top and middle panels, respectively).
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ABCB3 p.Lys509Met 12501238:164:172
status: NEW174 eYFP complexes (Fig. 4E, bottom panel), a corresponding distinct signal was not visualized in the TAP1(K544M)/ TAP2(K509M) combination (Fig. 4E, middle panel), despite the higher expression of TAP1(K544M) in the latter complexes.
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ABCB3 p.Lys509Met 12501238:174:116
status: NEW185 Using TAP1-eGFP/TAP2(K509M) complexes under conditions of TAP1 excess or TAP2 excess (Fig. 2), we determined that the two nucleotide-binding sites of TAP1/TAP2 complexes did in fact bind 8-azido-ATP with apparent affinities that were, within the error of these measurements, quite similar to each other.
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ABCB3 p.Lys509Met 12501238:185:21
status: NEW202 The absence of a signal was not due to the expression level, as TAP1(K544M) was expressed at higher levels in the microsomes with the TAP2(K509M) combination compared with the TAP2-eYFP combination (see D).
X
ABCB3 p.Lys509Met 12501238:202:139
status: NEW210 Mutation of the TAP2 Walker A lysine residue (TAP2(K509M)) indeed influenced nucleotide binding at the TAP2 site (Fig. 2).
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ABCB3 p.Lys509Met 12501238:210:51
status: NEW215 However, co-expression of TAP1(K544M) with TAP2(K509M) resulted in a nucleotide-binding deficient complex (Ref. 7 and Fig. 4).
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ABCB3 p.Lys509Met 12501238:215:48
status: NEW217 What mechanisms could be responsible for enhanced TAP1 labeling in TAP1(K544M)/TAP2-eYFP complexes compared with TAP1(K544M)/TAP2(K509M) complexes?
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ABCB3 p.Lys509Met 12501238:217:130
status: NEW222 When we compared 8-azido-[ॹ-32 P]ATP binding by TAP1-eGFP in TAP1-eGFP/TAP2 complexes and TAP1-eGFP/ TAP2(K509M) complexes, we found that the TAP1-eGFP labeling intensity was enhanced when in complex with wild type TAP2 compared with TAP2(K509M).
X
ABCB3 p.Lys509Met 12501238:222:112
status: NEWX
ABCB3 p.Lys509Met 12501238:222:245
status: NEW226 Thus, the TAP2(K509M) mutation appears to have distinct effects on labeling of TAP1 compared with TAP1(K544M).
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ABCB3 p.Lys509Met 12501238:226:15
status: NEW238 High affinity labeling of TAP1(K544M) residues in TAP1(K544M)/TAP2-eYFP complexes (Fig. 4), but not of TAP2(K509M) residues in TAP1-eGFP/TAP2(K509M) complexes (Fig. 2), might arise because of conformational differences between the two mutant complexes.
X
ABCB3 p.Lys509Met 12501238:238:108
status: NEWX
ABCB3 p.Lys509Met 12501238:238:142
status: NEW251 The analyses undertaken here also allow for a reassessment of the effects of TAP1(K544M) and TAP2(K509M) mutations upon peptide binding to TAP1/TAP2 complexes.
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ABCB3 p.Lys509Met 12501238:251:98
status: NEW253 Both mutant complexes were found to bind TAP-specific peptides with high affinity at room temperature (5); however, whereas the binding affinity of the TAP1(K544M)/TAP2 complex (KD afd; 17.4 afe; 4.8 nM) was very similar to wild type (KD afd; 19.4 afe; 4.8 nM), the affinity of the TAP1/TAP2(K509M) was b03;2-fold reduced (KD afd; 39.2 afe; 5.9 nM).
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ABCB3 p.Lys509Met 12501238:253:304
status: NEW
PMID: 11099504
[PubMed]
Lapinski PE et al: "Walker A lysine mutations of TAP1 and TAP2 interfere with peptide translocation but not peptide binding."
No.
Sentence
Comment
2
Mutants TAP1(K544M) and TAP2(K509M) were expressed in insect cells, and the effects of the mutations on nucleotide binding, peptide binding, and peptide translocation were assessed.
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ABCB3 p.Lys509Met 11099504:2:29
status: NEW7 Peptide translocation is undetectable for TAP1⅐TAP2(K509M) complexes, but low levels of translocation are detectable with TAP1(K544M)⅐TAP2 complexes.
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ABCB3 p.Lys509Met 11099504:7:58
status: NEW44 Toward a definition of the requirement for nucleotide binding and hydrolysis by each TAP subunit for peptide binding and translocation, we generated mutants of TAP1 (K544M) and TAP2 (K509M) that were altered at a conserved lysine residue of the Walker A motif (GXXGXGK(S/T)) of each protein.
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ABCB3 p.Lys509Met 11099504:44:183
status: NEW47 We observe that the Walker A lysine mutations in TAP1 and TAP2 have distinct effects upon nucleotide binding to each subunit, with nucleotide binding being significantly impaired in the TAP1(K544M) mutant but not in the TAP2(K509M) mutant.
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ABCB3 p.Lys509Met 11099504:47:225
status: NEW111 Recombinant baculoviruses were generated encoding histidine-tagged TAP1 (TAP1-His), the corresponding Walker A lysine mutant (TAP1(K544M)-His), and the TAP2 Walker A lysine mutant (TAP2(K509M)).
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ABCB3 p.Lys509Met 11099504:111:186
status: NEW114 For comparisons of nucleotide binding by each mutant or wild type TAP subunit, insect cells were infected with baculoviruses encoding TAP1-His, TAP1(K544M)- His, TAP2, or TAP2(K509M) for ϳ72 h.
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ABCB3 p.Lys509Met 11099504:114:176
status: NEW121 By contrast, TAP2(K509M) binding to ATP and ADP beads does not appear to be significantly impaired relative to wild type TAP2 (Fig. 1B, lanes 1 and 2 compared with lanes 5 and 6).
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ABCB3 p.Lys509Met 11099504:121:18
status: NEW128 Likewise, TAP2(K509M) associates with TAP1 as does wild type TAP2, as measured by coimmunoprecipitation analyses with the TAP1-specific antibody 148.3 (anti-TAP1) (9) and anti-TAP2 (Fig. 2B).
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ABCB3 p.Lys509Met 11099504:128:15
status: NEW139 Binding of TAP1-His, TAP1(K544M)-His, TAP2, and TAP2(K509M) to nucleotide-agarose beads.
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ABCB3 p.Lys509Met 11099504:139:53
status: NEW143 B, lanes 1 and 2 show that TAP2 binds to ATP and ADP. Lanes 5 and 6 show that the binding pattern for TAP2(K509M) is similar to wild type TAP2 and indicate that the mutant is not deficient in nucleotide binding.
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ABCB3 p.Lys509Met 11099504:143:107
status: NEW144 (K509M) complexes were impaired for translocation.
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ABCB3 p.Lys509Met 11099504:144:1
status: NEWX
ABCB3 p.Lys509Met 11099504:144:107
status: NEW145 Impaired translocation by TAP1⅐TAP2(K509M) complexes was not due to reduced expression of either TAP1 or TAP2 (Fig. 3B).
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ABCB3 p.Lys509Met 11099504:145:41
status: NEW146 Indeed, microsomes containing TAP1-His150;TAP2 complexes yielded higher cpmϩATP/cpm-ATP ratios, although the expression levels of TAP1 and TAP2 were significantly lower than that present in microsomal preparations of TAP1⅐TAP2(K509M) complexes (Fig. 3B, compare lane 2 with lane 3).
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ABCB3 p.Lys509Met 11099504:146:42
status: NEWX
ABCB3 p.Lys509Met 11099504:146:244
status: NEW158 In the experiments shown in Fig. 4, A and C, the same microsome preparations of TAP1⅐TAP2 and TAP1⅐TAP2(K509M) were used as for the translocation assays shown in Fig. 3 (Fig. 3B, lanes 1 and 2).
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ABCB3 p.Lys509Met 11099504:158:118
status: NEW165 B, TAP1⅐TAP2, or TAP1⅐TAP2(K509M) interactions.
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ABCB3 p.Lys509Met 11099504:165:41
status: NEW172 In three independent translocation experiments, the average cpmϩATP/cpm-ATP ratios for TAP1(K544M)-His⅐TAP2 complexes were 2-fold higher than for single subunit controls, whereas the average cpmϩATP/cpm-ATP ratios for TAP1⅐TAP2(K509M) complexes were at the same level as the single subunit controls.
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ABCB3 p.Lys509Met 11099504:172:254
status: NEW175 The resulting blot shows that while no translocation signal is observable for TAP1⅐TAP2(K509M) complexes, both TAP subunits are expressed at levels comparable with the wild type complex (compare lanes 1 and 2).
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ABCB3 p.Lys509Met 11099504:175:95
status: NEW198 For wild type TAP1⅐TAP2 and TAP1⅐TAP2(K509M), the same microsomes were used as in the translocation assays indicated in Fig. 3.
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ABCB3 p.Lys509Met 11099504:198:52
status: NEW200 The total protein concentration on each microsome preparation was 0.7 mg/ml TAP1⅐TAP2 (A), 1.8 mg/ml TAP1(K544M)-His⅐TAP2 (B), 1.3 mg/ml TAP1⅐TAP2(K509M) (C), and 1.3 mg/ml uninfected (D).
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ABCB3 p.Lys509Met 11099504:200:168
status: NEW204 The calculated binding constants for the TAP1⅐TAP2(K509M) mutant indicated that the peptide binding affinity of this mutant was slightly weaker compared with wild type TAP complexes.
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ABCB3 p.Lys509Met 11099504:204:58
status: NEW215 We observed that the TAP1(K544M) mutation significantly reduced nucleotide binding by TAP1 but that the TAP2(K509M) mutation did not significantly alter nucleotide binding by TAP2.
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ABCB3 p.Lys509Met 11099504:215:109
status: NEW220 Here we report that the K509M mutation in TAP2 abrogates peptide transport by TAP1⅐TAP2(K509M) complexes, although ATP binding by this mutant is not significantly different from wild type.
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ABCB3 p.Lys509Met 11099504:220:24
status: NEWX
ABCB3 p.Lys509Met 11099504:220:95
status: NEW221 Impairment in peptide translocation does not arise from structural disruptions induced by the mutation, since TAP1⅐TAP2(K509M) complexes are capable of binding both peptides and nucleotides (Figs. 1 and 3).
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ABCB3 p.Lys509Met 11099504:221:24
status: NEWX
ABCB3 p.Lys509Met 11099504:221:94
status: NEWX
ABCB3 p.Lys509Met 11099504:221:127
status: NEW222 Furthermore, based upon limited proteolytic digestion analysis, the proteolysis profiles observed for TAP1⅐TAP2(K509M) complexes closely parallel the profiles seen for TAP1⅐TAP2 complexes.2 Thus, nucleotide hydrolysis by TAP complexes containing mutant TAP2 appears to be impaired.
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ABCB3 p.Lys509Met 11099504:222:119
status: NEWX
ABCB3 p.Lys509Met 11099504:222:126
status: NEW231 The total protein concentration on each microsome preparation was 0.7 mg/ml TAP1⅐TAP2 (A), 1.1 mg/ml TAP1(K544M)-His⅐TAP2 (B), and 1.3 mg/ml TAP1⅐TAP2(K509M) (C).
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ABCB3 p.Lys509Met 11099504:231:172
status: NEW234 By similar criteria, four separate sets of experiments comparing peptide binding by TAP1⅐TAP2(K509M) microsomes and uninfected microsomes verify that this mutant complex is also capable of binding peptides.
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ABCB3 p.Lys509Met 11099504:234:101
status: NEW244 The observation that the TAP2(K509M) mutation impairs translocation by TAP1⅐TAP2(K509M) complexes although no residue alterations were introduced into TAP1 indicates that the ATPase activity at TAP1, if present, is insufficient for completion of a peptide translocation cycle. Taken together with the observation that the TAP1(K544M) mutation significantly reduces peptide translocation efficiency of TAP complexes when no residue modifications are introduced into TAP2, these results indicate a coupling between nucleotide interactions with TAP1 and TAP2.
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ABCB3 p.Lys509Met 11099504:244:30
status: NEWX
ABCB3 p.Lys509Met 11099504:244:88
status: NEW259 It is interesting that the TAP2(K509M) mutation abrogates peptide translocation by TAP1⅐TAP2(K509M) complexes but that the TAP1 mutant with a significant impairment in TAP1 nucleotide binding appears to, with low efficiency, mediate peptide translocation by TAP1(K544M)-His⅐TAP2 complexes.
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ABCB3 p.Lys509Met 11099504:259:32
status: NEWX
ABCB3 p.Lys509Met 11099504:259:100
status: NEW268 Using similar sets of fluorescence quenching assays, we show here that TAP1(K544M)- His⅐TAP2 and TAP1⅐TAP2(K509M) complexes are capable of binding peptides, although the binding affinity of TAP1⅐TAP2(K509M) complexes appears weaker than wild type.
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ABCB3 p.Lys509Met 11099504:268:121
status: NEWX
ABCB3 p.Lys509Met 11099504:268:221
status: NEW112 Recombinant baculoviruses were generated encoding histidine-tagged TAP1 (TAP1-His), the corresponding Walker A lysine mutant (TAP1(K544M)-His), and the TAP2 Walker A lysine mutant (TAP2(K509M)).
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ABCB3 p.Lys509Met 11099504:112:186
status: NEW115 For comparisons of nucleotide binding by each mutant or wild type TAP subunit, insect cells were infected with baculoviruses encoding TAP1-His, TAP1(K544M)- His, TAP2, or TAP2(K509M) for b03;72 h.
X
ABCB3 p.Lys509Met 11099504:115:176
status: NEW122 By contrast, TAP2(K509M) binding to ATP and ADP beads does not appear to be significantly impaired relative to wild type TAP2 (Fig. 1B, lanes 1 and 2 compared with lanes 5 and 6).
X
ABCB3 p.Lys509Met 11099504:122:18
status: NEW129 Likewise, TAP2(K509M) associates with TAP1 as does wild type TAP2, as measured by coimmunoprecipitation analyses with the TAP1-specific antibody 148.3 (anti-TAP1) (9) and anti-TAP2 (Fig. 2B).
X
ABCB3 p.Lys509Met 11099504:129:15
status: NEW140 Binding of TAP1-His, TAP1(K544M)-His, TAP2, and TAP2(K509M) to nucleotide-agarose beads.
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ABCB3 p.Lys509Met 11099504:140:53
status: NEW147 Indeed, microsomes containing TAP1-HisዼTAP2 complexes yielded higher cpmaf9;ATP/cpmafa;ATP ratios, although the expression levels of TAP1 and TAP2 were significantly lower than that present in microsomal preparations of TAP1ዼTAP2(K509M) complexes (Fig. 3B, compare lane 2 with lane 3).
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ABCB3 p.Lys509Met 11099504:147:248
status: NEW159 In the experiments shown in Fig. 4, A and C, the same microsome preparations of TAP1ዼTAP2 and TAP1ዼTAP2(K509M) were used as for the translocation assays shown in Fig. 3 (Fig. 3B, lanes 1 and 2).
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ABCB3 p.Lys509Met 11099504:159:116
status: NEW166 B, TAP1ዼTAP2, or TAP1ዼTAP2(K509M) interactions.
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ABCB3 p.Lys509Met 11099504:166:39
status: NEW173 In three independent translocation experiments, the average cpmaf9;ATP/cpmafa;ATP ratios for TAP1(K544M)-HisዼTAP2 complexes were 2-fold higher than for single subunit controls, whereas the average cpmaf9;ATP/cpmafa;ATP ratios for TAP1ዼTAP2(K509M) complexes were at the same level as the single subunit controls.
X
ABCB3 p.Lys509Met 11099504:173:264
status: NEW176 The resulting blot shows that while no translocation signal is observable for TAP1ዼTAP2(K509M) complexes, both TAP subunits are expressed at levels comparable with the wild type complex (compare lanes 1 and 2).
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ABCB3 p.Lys509Met 11099504:176:94
status: NEW199 For wild type TAP1ዼTAP2 and TAP1ዼTAP2(K509M), the same microsomes were used as in the translocation assays indicated in Fig. 3.
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ABCB3 p.Lys509Met 11099504:199:50
status: NEW201 The total protein concentration on each microsome preparation was 0.7 mg/ml TAP1ዼTAP2 (A), 1.8 mg/ml TAP1(K544M)-HisዼTAP2 (B), 1.3 mg/ml TAP1ዼTAP2(K509M) (C), and 1.3 mg/ml uninfected (D).
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ABCB3 p.Lys509Met 11099504:201:165
status: NEW205 The calculated binding constants for the TAP1ዼTAP2(K509M) mutant indicated that the peptide binding affinity of this mutant was slightly weaker compared with wild type TAP complexes.
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ABCB3 p.Lys509Met 11099504:205:57
status: NEW216 We observed that the TAP1(K544M) mutation significantly reduced nucleotide binding by TAP1 but that the TAP2(K509M) mutation did not significantly alter nucleotide binding by TAP2.
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ABCB3 p.Lys509Met 11099504:216:109
status: NEW223 Furthermore, based upon limited proteolytic digestion analysis, the proteolysis profiles observed for TAP1ዼTAP2(K509M) complexes closely parallel the profiles seen for TAP1ዼTAP2 complexes.2 Thus, nucleotide hydrolysis by TAP complexes containing mutant TAP2 appears to be impaired.
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ABCB3 p.Lys509Met 11099504:223:118
status: NEW232 The total protein concentration on each microsome preparation was 0.7 mg/ml TAP1ዼTAP2 (A), 1.1 mg/ml TAP1(K544M)-HisዼTAP2 (B), and 1.3 mg/ml TAP1ዼTAP2(K509M) (C).
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ABCB3 p.Lys509Met 11099504:232:169
status: NEW235 By similar criteria, four separate sets of experiments comparing peptide binding by TAP1ዼTAP2(K509M) microsomes and uninfected microsomes verify that this mutant complex is also capable of binding peptides.
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ABCB3 p.Lys509Met 11099504:235:100
status: NEW245 The observation that the TAP2(K509M) mutation impairs translocation by TAP1ዼTAP2(K509M) complexes although no residue alterations were introduced into TAP1 indicates that the ATPase activity at TAP1, if present, is insufficient for completion of a peptide translocation cycle. Taken together with the observation that the TAP1(K544M) mutation significantly reduces peptide translocation efficiency of TAP complexes when no residue modifications are introduced into TAP2, these results indicate a coupling between nucleotide interactions with TAP1 and TAP2.
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ABCB3 p.Lys509Met 11099504:245:30
status: NEWX
ABCB3 p.Lys509Met 11099504:245:87
status: NEW260 It is interesting that the TAP2(K509M) mutation abrogates peptide translocation by TAP1ዼTAP2(K509M) complexes but that the TAP1 mutant with a significant impairment in TAP1 nucleotide binding appears to, with low efficiency, mediate peptide translocation by TAP1(K544M)-HisዼTAP2 complexes.
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ABCB3 p.Lys509Met 11099504:260:32
status: NEWX
ABCB3 p.Lys509Met 11099504:260:99
status: NEW269 Using similar sets of fluorescence quenching assays, we show here that TAP1(K544M)- HisዼTAP2 and TAP1ዼTAP2(K509M) complexes are capable of binding peptides, although the binding affinity of TAP1ዼTAP2(K509M) complexes appears weaker than wild type.
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ABCB3 p.Lys509Met 11099504:269:119
status: NEWX
ABCB3 p.Lys509Met 11099504:269:218
status: NEW
PMID: 11250152
[PubMed]
Alberts P et al: "Distinct functional properties of the TAP subunits coordinate the nucleotide-dependent transport cycle."
No.
Sentence
Comment
239
The authors showof T2 containing rat TAP1a and rat TAP2a , which have been described that mutation K607M in TAP1 and K509M in TAP2, which are differentpreviously [37], were cultured in IMDM (Gibco BRL) supplemented with from our mutations, have distinct effects on nucleotide binding and peptide 10% FCS (BIO Whittaker) and 1 mg/ml G418 (PAA, Co¨lbe).
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ABCB3 p.Lys509Met 11250152:239:117
status: NEW