ABCC7 p.Asp836*
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PMID: 10962022
[PubMed]
Csanady L et al: "Severed channels probe regulation of gating of cystic fibrosis transmembrane conductance regulator by its cytoplasmic domains."
No.
Sentence
Comment
337
Interestingly, a half-channel truncated at that same cut site (D836X; Sheppard et al., 1994) also showed a low level of constitutive activity, but was strongly activated by PKA, and had a high apparent affinity for ATP, properties reminiscent of those described here for 835ϩ837 channels.
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ABCC7 p.Asp836* 10962022:337:63
status: NEW
PMID: 18421494
[PubMed]
Cui G et al: "Mutations at arginine 352 alter the pore architecture of CFTR."
No.
Sentence
Comment
274
However, other authors reported that the amino-terminal portion of CFTR, containing MSD1, NBD1 and the R domain (D836X-CFTR), formed regulated Cl-channels that differed somewhat from WT-CFTR (Sheppard et al. 1994).
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ABCC7 p.Asp836* 18421494:274:113
status: NEW275 Although the substate behavior of D836X-CFTR was not studied in detail, this mutant was reported to show instability of the open state compared to WT-CFTR; the authors suggested that residues in MSD2 might stabilize the channel complex, perhaps assisting in the arrangement of residues in MSD1 into a functional structure, based on the finding that the number of functional Cl-channels generated from the D836X construct was much lower than expected for WT-CFTR.
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ABCC7 p.Asp836* 18421494:275:34
status: NEWX
ABCC7 p.Asp836* 18421494:275:405
status: NEW
PMID: 9790686
[PubMed]
Clancy JP et al: "Cystic fibrosis transmembrane conductance regulator (CFTR) nucleotide-binding domain 1 (NBD-1) and CFTR truncated within NBD-1 target to the epithelial plasma membrane and increase anion permeability."
No.
Sentence
Comment
227
On the other hand, Sheppard et al. have demonstrated that a truncated CFTR molecule containing TM-1, NBD-1, and the R domain (D836X) remains capable of forming anion-selective channels with phosphorylation-dependent regulation (49).
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ABCC7 p.Asp836* 9790686:227:126
status: NEW
No.
Sentence
Comment
131
The amino-terminal portion of CFTR (D836X, which contains MSD1, NBD1 andfraction behavior of CFTR was lost (128).
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ABCC7 p.Asp836* 9922375:131:36
status: NEW136 Based on biochemical and functional data, we speculated that D836X generates a Cl0 channel byveats noted above regarding the contribution of residues to the pore versus less specific alterations of structure forming a homomultimer (116).
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ABCC7 p.Asp836* 9922375:136:61
status: NEW138 To identify residues that line the CFTR pore and make below), then in a D836X multimer MSD1 sequences may substitute for MSD2 sequences to form the pore.
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ABCC7 p.Asp836* 9922375:138:72
status: NEW504 First, those sites were phosphor- interference between R domains in a D836X homomultimer.ylated in vivo after stimulation with cAMP agonists.
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ABCC7 p.Asp836* 9922375:504:70
status: NEW526 In addition, deletion studies of portions of the R domain suggest thatout that PKA cannot interact with CFTRDR-S660A, even though it does interact with CFTRDR. there are two halves to the R domain with the first conserved in other ABC transporters and the second uniqueLike CFTRDR, the amino-terminal portion of CFTR (D836X, which contains MSD1, NBD1, and the R domain) to CFTR (102, 103).
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ABCC7 p.Asp836* 9922375:526:318
status: NEW528 The activation of D836X Cl0 channels by PKA indicates that E. A Model of R Domain Functionthe MSD1-NBD1 motif must contain many of the sequences with which the R domain interacts to control CFTR.
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ABCC7 p.Asp836* 9922375:528:18
status: NEW529 The PKA-independent activity of D836X Cl0 chan- The R domain was originally proposed to regulate CFTR by keeping the channel closed at rest.
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ABCC7 p.Asp836* 9922375:529:32
status: NEW533 Alternatively, the PKA-independent activity of D836X could be due to As described above, phosphorylation by PKA, deletion of FIG. 11 Effect of a recombinant R domain (R1, residues 645-834) on CFTRDR/S660A channel in presence of PKA.
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ABCC7 p.Asp836* 9922375:533:47
status: NEW
PMID: 17707141
[PubMed]
van Barneveld A et al: "CFTR protein analysis of splice site mutation 2789+5 G-A."
No.
Sentence
Comment
63
The recombinant N-terminal portion of CFTR (D836X) forms proper chloride channels in vitro [13], albeit the cooperation between the two non-equivalent NBDs in the binding and hydrolysis of nucleotides cannot take place [9].
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ABCC7 p.Asp836* 17707141:63:44
status: NEW
PMID: 10692317
[PubMed]
Xie J et al: "Conformation, independent of charge, in the R domain affects cystic fibrosis transmembrane conductance regulator channel openings."
No.
Sentence
Comment
272
Although other CFTR mutants have chloride transport in excess of WT CFTR, they are either not processed efficiently (e.g., P574H or H949Y) (Sheppard et al., 1996a, b; Seibert et al., 1996) or open without PKA stimulation (e.g., CFTR-D836X), and thus are not subject to physiologic regulation (Sheppard et al., 1994).
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ABCC7 p.Asp836* 10692317:272:233
status: NEW274 Although other CFTR mutants have chloride transport in excess of WT CFTR, they are either not processed efficiently (e.g., P574H or H949Y) (Sheppard et al., 1996a, b; Seibert et al., 1996) or open without PKA stimulation (e.g., CFTR-D836X), and thus are not subject to physiologic regulation (Sheppard et al., 1994).
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ABCC7 p.Asp836* 10692317:274:233
status: NEW
PMID: 10564718
[PubMed]
Pollet JF et al: "Expression and intracellular processing of chimeric and mutant CFTR molecules."
No.
Sentence
Comment
27
Nevertheless, the CFTR truncation mutant (D836X), which contains the 'rst MSD, NBD1, and the R domain, is capable of forming regulated Cl3 channels when expressed in HeLa cells [22] and the protein was shown to cosediment with mature CFTR on a sucrose gradient, suggesting that this 'rst half of the CFTR forms homodimers.
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ABCC7 p.Asp836* 10564718:27:42
status: NEW
PMID: 9879057
[PubMed]
Gallet X et al: "Topological model of membrane domain of the cystic fibrosis transmembrane conductance regulator."
No.
Sentence
Comment
229
Nevertheless, one paper demonstrates that mutant D836X encodes a truncated protein (up to amino acid D836, i.e., including MSD1, NBD1, and the R domain but not MSD2 and NBD2).
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ABCC7 p.Asp836* 9879057:229:49
status: NEW233 Nevertheless, one paper demonstrates that mutant D836X encodes a truncated protein (up to amino acid D836, i.e., including MSD1, NBD1, and the R domain but not MSD2 and NBD2).
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ABCC7 p.Asp836* 9879057:233:49
status: NEW
No.
Sentence
Comment
144
(1994) who created an artificial mutant CFTR missing TMD2 and NBD2 but containingthe R domain (D836X).
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ABCC7 p.Asp836* 9511929:144:95
status: NEW
PMID: 8810276
[PubMed]
Price MP et al: "Function of Xenopus cystic fibrosis transmembrane conductance regulator (CFTR) Cl channels and use of human-Xenopus chimeras to investigate the pore properties of CFTR."
No.
Sentence
Comment
254
5) We have shown that a CFTR construct containing only MSD1, NBD1, and the R domain (D836X) could form a Cl- channel with relatively normal conductive and permeability properties, albeit the efficiency of production was greatly reduced and regulation was altered (29).
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ABCC7 p.Asp836* 8810276:254:85
status: NEW278 This speculation is also consistent with our previous studies of D836X (29).
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ABCC7 p.Asp836* 8810276:278:65
status: NEW273 5) We have shown that a CFTR construct containing only MSD1, NBD1, and the R domain (D836X) could form a Cl2 channel with relatively normal conductive and permeability properties, albeit the efficiency of production was greatly reduced and regulation was altered (29).
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ABCC7 p.Asp836* 8810276:273:85
status: NEW297 This speculation is also consistent with our previous studies of D836X (29).
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ABCC7 p.Asp836* 8810276:297:65
status: NEW
PMID: 8764323
[PubMed]
Morales MM et al: "Both the wild type and a functional isoform of CFTR are expressed in kidney."
No.
Sentence
Comment
323
These data are in agreement with those recently published by Sheppard et al. (28) who created an artificial mutant CFTR missing TMD2 and NBD2 but containing the R domain (D836X).
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ABCC7 p.Asp836* 8764323:323:171
status: NEW
PMID: 8844211
[PubMed]
Duarte A et al: "Complex cystic fibrosis allele R334W-R1158X results in reduced levels of correctly processed mRNA in a pancreatic sufficient patient."
No.
Sentence
Comment
80
The fact that a truncated CFTR protein may have conductive properties was shown by the Iowa group (Sheppard et al., 1994) for the CETR protein resulting from the D836X mutation (exon 14a), which contains only its N-terminal part (the membrane-spanning domains 1-6, the first ATP-binding fold, and the regulatoryregion).
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ABCC7 p.Asp836* 8844211:80:162
status: NEW
PMID: 7511062
[PubMed]
Sheppard DN et al: "The amino-terminal portion of CFTR forms a regulated Cl- channel."
No.
Sentence
Comment
17
To test whether the amino-terminal portion of CFfR could form a regulated Cl- channel, we constructed the CFTR mutant D836X.
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ABCC7 p.Asp836* 7511062:17:118
status: NEW20 We used two antibodies: M13-1 against the R domain, which is present in D636X, and M24-1 against the carboxyl terminus, which is absent in D836X.
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ABCC7 p.Asp836* 7511062:20:139
status: NEW30 Under basal conditions, whole-cell currents from cells expressing D836X had a relatively linear current-voltage (I-V) relationship and a reversal potential consistent with Cl--selectivity, whereas basal whole-cell currents from cells expressing wild-type CFTR were much less Clse- lective (Table 1).
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ABCC7 p.Asp836* 7511062:30:66
status: NEW32 The anion permeability and conductance sequences of D836X whole-cell currents were similar to those of wild-type CFTR (Br > Cl- > I-; Table 1).
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ABCC7 p.Asp836* 7511062:32:52
status: NEW42 After excision of membrane patches from cells expressing D836X, we observed no channel activity.
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ABCC7 p.Asp836* 7511062:42:57
status: NEW45 Phosphorylation with PKA (75 nM) significantly increased the P, of D836X channels.
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ABCC7 p.Asp836* 7511062:45:67
status: NEW48 These data suggest that some aspects of the relationship between the R domain and the rest of the channel may be altered in D836X, while others may remain intact.
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ABCC7 p.Asp836* 7511062:48:124
status: NEW51 The single-channel slope conductance of D836X (8.03 * 0.23 pS; n = 8) was not different from that of wild-type CFTR (8.29 -c 0.15 pS; n = 4).
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ABCC7 p.Asp836* 7511062:51:40
status: NEW54 Consistent with this interpretation is the finding that CAMP-activated whole-cell currents were observed in 10 of 59 cells expressing D836X (17%) compared with 10 of 14 cells expressing wild-type CFTR (71%).
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ABCC7 p.Asp836* 7511062:54:134
status: NEW58 Because D836X lacks NBDZ, we speculated that the interaction with intracellular nucleotides might be altered.
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ABCC7 p.Asp836* 7511062:58:8
status: NEW63 As we previously reported for wild-type CFTR (Anderson and Welsh, 1992), an Eadie-Hofstee plot of the D836X data generated a curved line(Figure 3C).
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ABCC7 p.Asp836* 7511062:63:102
status: NEW67 Figures 4A and 48 show that intracellular ADP (1 mM) produced equivalent reductions in the activity of both D836X and wild-type channels.
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ABCC7 p.Asp836* 7511062:67:108
status: NEW68 D636X Sediments as a Multlmer on Sucrose Gradient Centrlfugatlon Based on these results and considerations discussed below, we asked whether D836X might exist as a multimer.
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ABCC7 p.Asp836* 7511062:68:141
status: NEW71 1094 A ATP D836X ...... PKA + ATP Is CFTR ATP _..... PKA + ATP _._... B 0.6 0.4 PO 0.2 0 0.6 0.4 PO 0.2 0 I CFTR \TP PKA + ATP ATP PKA + ATP Figure 2.
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ABCC7 p.Asp836* 7511062:71:11
status: NEW81 These sedimentation patterns A D836X C ~PAL 1s 0.4 PO 0.2 0 :;::::` 0 pl&~P] (2) 4.0 c k 5 2.0 n" 0 -_i 0 0.40.2 PO Figure 3.
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ABCC7 p.Asp836* 7511062:81:31
status: NEW95 However, our previous data suggest that full-length CFTR does not associate to form a multimer ;h&mino-Terminal Half of CFTR Forms a Cl- Channel A D836X ATP CFTR B ---- - IS 1s Figure 4.
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ABCC7 p.Asp836* 7511062:95:148
status: NEW96 Intracellular ADP Inhibits D&36X Cl- Channels (A) Comparison of the effect of ADP on the activity of three D836X Cl- channels and a single wild-type Cl- channel following PKAdependent phosphorylation.
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ABCC7 p.Asp836* 7511062:96:107
status: NEW98 ATP (0.88 mM MgATP) and ADP (1 mM) were added to the intracellular solution as indicated. Voltage was -86 mV (D836X) and -83 mV (CFTR), respectively.
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ABCC7 p.Asp836* 7511062:98:110
status: NEW101 Voltage was -86 f 1 mV (D836X) and -85 * 2 mV (CFTR).
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ABCC7 p.Asp836* 7511062:101:24
status: NEW124 The Membrane-Spanning Domains The conductive properties of Cl- channels formed by D636X were remarkably similar to those of wild-type CFTR: the channels had the same anion-to-cation permeability, anion selectivity sequence, single-channel conduc- 1096 A kDa 210 170 116 94 76 67 i B kDa 210 170 116 94 76 57 D836X 6% MO% Total % Sucrow Lysate CFTR % Sucrose ~0% Total Lysate 246 kDa 9/oSucrose - 20% Figure 5.
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ABCC7 p.Asp836* 7511062:124:310
status: NEW141 We found that although large amountsof protein were produced in cellsexpressing D836X, the number of functional Cl- channels generated was much less than that observed with wild-type CFfR.
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ABCC7 p.Asp836* 7511062:141:80
status: NEW142 Thus, D836X was not as efficient as wild type at generating functional channels.
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ABCC7 p.Asp836* 7511062:142:6
status: NEW149 Could a CF-associated mutant that made protein with properties similar to those of D836X produce sufficient residual activity to confer a milder clinical phenotype?
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ABCC7 p.Asp836* 7511062:149:83
status: NEW150 Given the limited expression of functional D836X Cl- channels despite relatively high-level protein expression, such a possibility seems unlikely.
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ABCC7 p.Asp836* 7511062:150:43
status: NEW