ABCC7 p.Gly551Cys
[switch to full view]Comments [show]
None has been submitted yet.
PMID: 19114635
[PubMed]
Wang X et al: "Mutations at the signature sequence of CFTR create a Cd(2+)-gated chloride channel."
No.
Sentence
Comment
22
The mutants G551C, L548C, and S549C, all in the signature sequence of CFTR`s NBD1, show robust response to Cd2+ .
X
ABCC7 p.Gly551Cys 19114635:22:12
status: NEW49 For the G551C and S549C mutants, because they are ATP dependent, we used the current in the presence of 1 mM ATP as control.
X
ABCC7 p.Gly551Cys 19114635:49:8
status: NEW55 The apparent affinity for Cd2+ was further increased when glycine 551 was converted to cysteine, but the effect of Cd2+ was mostly abolished when the G551 residue was substituted by an alanine.
X
ABCC7 p.Gly551Cys 19114635:55:58
status: NEW94 On the other hand, 10 μM Cd2+ already generates a maximal response for G551C-CFTR, with a maximal fold increase of 7.4 ± 0.3 (n = 5) compared with the currents generated by 1 mM ATP. Fitting the dose-response relationships with the Hill equation yields a K1/2 of 14.6 ± 6.3 μM and 3.29 ± 0.66 μM for G551D and G551C, respectively.
X
ABCC7 p.Gly551Cys 19114635:94:77
status: NEWX
ABCC7 p.Gly551Cys 19114635:94:343
status: NEW96 Like the G551C mutant, G551A-CFTR remains responsive to ATP.
X
ABCC7 p.Gly551Cys 19114635:96:9
status: NEW97 However, the effect of Cd2+ on G551A-CFTR is negligibly small compared with that of G551C-CFTR (Fig. 5 A vs. Fig. 4 B).
X
ABCC7 p.Gly551Cys 19114635:97:84
status: NEW98 This difference between G551A and G551C was quantified in Fig. 5 B, where we compared the current generated by 1 mM ATP with the current generated by 10 μM Cd2+ for these two mutants.
X
ABCC7 p.Gly551Cys 19114635:98:34
status: NEW107 However, for L548C, S549C, and G551C, the specificity of the ligand is altered so that Cd2+ becomes more effective at gating Cd2+ Is More Potent on G551C than on G551D We considered two possible mechanisms for the effect of Cd2+ on G551D-CFTR.
X
ABCC7 p.Gly551Cys 19114635:107:31
status: NEWX
ABCC7 p.Gly551Cys 19114635:107:148
status: NEW111 To differentiate these two possibilities, we first mutated the glycine at position 551 to cysteine.
X
ABCC7 p.Gly551Cys 19114635:111:63
status: NEW113 Fig. 4 shows representative traces of G551D (A) and G551C (B) in the presence of different [Cd2+ ].
X
ABCC7 p.Gly551Cys 19114635:113:52
status: NEW114 Note that 5 μM Cd2+ induces a higher G551C-CFTR current than 1 mM ATP, despite that this mutation retains responsiveness to ATP.
X
ABCC7 p.Gly551Cys 19114635:114:43
status: NEW132 The Binding Partner of Cd2+ Is Likely To Be a Cysteine Residue The micromolar affinity of Cd2+ in activating G551C or S549C mutants raises the possibility that some endogenous cysteine(s) or histidine(s) may participate in form- Figure 4.
X
ABCC7 p.Gly551Cys 19114635:132:109
status: NEW133 Representative current traces of G551D-CFTR (A) and G551C-CFTR (B) in the presence of different [Cd2+ ].
X
ABCC7 p.Gly551Cys 19114635:133:52
status: NEW134 The Cd2+ dose-response relationships for G551D-CFTR (C) and G551C-CFTR (D) were fitted with the Hill equation, y = min + (max-min)/ [1+ (K1/2/[x])n )] (smooth curves).
X
ABCC7 p.Gly551Cys 19114635:134:60
status: NEW135 The fold increase of the current in the presence of Cd2+ was normalized to the maximal fold increase for each mutant (G551D: 21.38 ± 4.19-fold, 100 μM Cd2+ ; G551C: 7.4 ± 0.3, 10 μM Cd2+ ).
X
ABCC7 p.Gly551Cys 19114635:135:169
status: NEW136 G551D: K1/2 = 14.6 ± 6.3 μM and n = 1.03 ± 0.34; G551C: K1/2 = 3.29 ± 0.66 μM and n = 1.89 ± 0.52.
X
ABCC7 p.Gly551Cys 19114635:136:65
status: NEW137 Figure 5. Comparison of Cd2+ and ATP-induced currents between G551A and G551C mutants.
X
ABCC7 p.Gly551Cys 19114635:137:72
status: NEW140 (B) The ratio of currents induced by 10 μM Cd2+ and those with 1 mM ATP for G551C-CFTR and G551A-CFTR.
X
ABCC7 p.Gly551Cys 19114635:140:82
status: NEW144 For G551C-CFTR, this effect of Cd2+ on the opening rate likely also occurs.
X
ABCC7 p.Gly551Cys 19114635:144:4
status: NEW145 The open time for G551C-CFTR in the absence of ATP is 202.6 ± 29.6 ms (n = 3).
X
ABCC7 p.Gly551Cys 19114635:145:18
status: NEW148 D I S C U S S I O N Here, we show that micromolar concentrations of Cd2+ can dramatically increase the activity of G551D-CFTR, a disease-associated mutant, as well as G551C-CFTR, L548C, and S549C-CFTR, in the absence of ATP.
X
ABCC7 p.Gly551Cys 19114635:148:167
status: NEW216 First, the apparent affinities for G551C and S549C are at low micromolar range, supporting the idea that multiple cysteines are involved in coordinating Cd2+ .
X
ABCC7 p.Gly551Cys 19114635:216:35
status: NEW
PMID: 19332488
[PubMed]
Hwang TC et al: "Gating of the CFTR Cl- channel by ATP-driven nucleotide-binding domain dimerisation."
No.
Sentence
Comment
119
Recently, Wang et al. (2009) demonstrated that cadmium (Cd2+ ) can act as a ligand to gate G551Dand G551C-CFTR by serving as a metal bridge connecting G551D/C to an unknown cysteine residue in CFTR.
X
ABCC7 p.Gly551Cys 19332488:119:100
status: NEW