ABCMdb

ABCC7 p.Pro740Ala

Predicted by SNAP2:	A: D (53%), C: D (59%), D: D (80%), E: D (80%), F: D (80%), G: D (80%), H: D (80%), I: D (80%), K: D (66%), L: D (80%), M: D (75%), N: D (75%), Q: D (71%), R: D (80%), S: D (71%), T: N (53%), V: D (75%), W: D (85%), Y: D (80%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: D, K: D, L: D, M: D, N: D, Q: D, R: D, S: D, T: D, V: D, W: D, Y: D,

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Publications
[hide] Conformation, independent of charge, in the R doma... Biophys J. 2000 Mar;78(3):1293-305. Xie J, Zhao J, Davis PB, Ma J
Conformation, independent of charge, in the R domain affects cystic fibrosis transmembrane conductance regulator channel openings.
Biophys J. 2000 Mar;78(3):1293-305., [PMID:10692317]

Abstract [show]
The R domain of cystic fibrosis transmembrane conductance regulator (CFTR), when phosphorylated, undergoes conformational change, and the chloride channel opens. We investigated the contribution of R domain conformation, apart from the changes induced by phosphorylation, to channel opening, by testing the effect of the peptidyl-prolyl isomerase, cyclophilin A, on the CFTR channel. When it was applied after the channel had been opened by PKA phosphorylation, cyclophilin A increased the open probability of wild-type CFTR (from P(o) = 0.197 +/- 0.010 to P(o) = 0.436 +/- 0. 029) by increasing the number of channel openings, not open time. Three highly conserved proline residues in the R domain, at positions 740, 750, and 759, were considered as candidate targets for cyclophilin A. Mutations of these prolines to alanines (P3A mutant) resulted in a channel unresponsive to cyclophilin A but with pore properties similar to the wild type, under strict control of PKA and ATP, but with significantly increased open probability (P(o) = 0.577 +/- 0.090) compared to wild-type CFTR, again due to an increase in the number of channel openings and not open time. Mutation of each of the proline residues separately and in pairs demonstrated that all three proline mutations are required for maximal P(o). When P3A was expressed in 293 HEK cells and tested by SPQ assay, chloride efflux was significantly increased compared to cells transfected with wild-type CFTR. Thus, treatments favoring the trans-peptidyl conformation about conserved proline residues in the R domain of CFTR affect openings of CFTR, above and beyond the effect of PKA phosphorylation.

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Sentences [show]
No. Sentence Comment
33 Site-specific mutations were constructed following the manufacturer`s instructions using the following three mutagenesis oligonucleotides (showed 5Ј to 3Ј, with mutated base underlined): P740A, G CTC AGA ATC TGC TAC TAA GGA CAG C (RsaI enzyme restriction site is destroyed); P750A, G GCT GAT GCG AGC CAG TAT CGC CTC (BsrI site is created); P759A/T757S, C CTG AAG CGT GGC CGG AGA GCT GAT (BsaHI site is created and BsrI site is destroyed). Login to comment
57 Vesicle preparation Six 75 cm2 flasks of 293 HEK cells transfected with either pCEP4(WT) or CFTR mutants (P3A, P2A, P740A, P750A, P759A) vectors were harvested and lysed following the procedure described previously (Xie et al., 1995, 1996). Login to comment
64 In experiments with WT, P3A, P2A, P740A, P750, and P759A, cis solution also contains 50 units/ml cAMP-dependent protein kinase A catalytic subunit. Login to comment
147 All three proline mutations are involved in the enhanced activity of the P3A CFTR channel To investigate which proline is critical for the increased open probability of the P3A channel, we constructed all three single proline mutants (P740A, P750A, P759A) and incorporated each of them into the planar lipid bilayer. Login to comment
149 Mutants P740A and P759A CFTR have similar open probability to WT CFTR, whereas P750A CFTR has significantly increased Po. Login to comment
153 P740A CFTR had Po similar to the wild type, while its mean open life time is significantly (p Ͻ 0.05) lower (closing faster) than that of the WT CFTR, so FIGURE 4 ATP-and PKA-dependent gating of the P3A CFTR channel. Login to comment
160 the P740A mutant must have a higher opening rate. Login to comment
196 The double (P2A; Fig. 10, lane 4) or single proline mutants (P740A, P750A, P759A; Fig. 10, lanes 5-7, respectively) were also fully glycosylated to a similar extent. Login to comment
229 The averaged values were Po ϭ 0.204 Ϯ 0.036 (WT), 0.438 Ϯ 0.029 (WT ϩ CyP (Cyclophilin A)), 0.577 Ϯ 0.090 (P3A CFTR), 0.161 Ϯ 0.018 (P740A), 0.426 Ϯ 0.030 (P750A), 0.166 Ϯ 0.034 (P759A), 0.272 Ϯ 0.059 (P2A), respectively. Login to comment
237 It is also FIGURE 10 Heterologous expression of wild-type CFTR and proline mutants in 293 HEK cells: 293 HEK cells transfected with pCEP4(WT), pCEP4(P3A), pCEP4(P2A), pCEP4(P740A), pCEP4(P750A), or pCEP4(P759A) were immunoprecipitated and blotted as described in the Materials and Methods; mAb24-1 that recognizes the C-terminus of CFTR was used in the immunoprecipitation/Western blot. Login to comment
239 Lane 1 (UNT): untransfected 293 HEK cells; lane 2: WT CFTR expressing cells; lanes 3-7: P3A, P2A, P740A, P750A, and P759A CFTR expressing cells, respectively. Login to comment
34 Site-specific mutations were constructed following the manufacturer`s instructions using the following three mutagenesis oligonucleotides (showed 5b18; to 3b18;, with mutated base underlined): P740A, G CTC AGA ATC TGC TAC TAA GGA CAG C (RsaI enzyme restriction site is destroyed); P750A, G GCT GAT GCG AGC CAG TAT CGC CTC (BsrI site is created); P759A/T757S, C CTG AAG CGT GGC CGG AGA GCT GAT (BsaHI site is created and BsrI site is destroyed). Login to comment
58 Vesicle preparation Six 75 cm2 flasks of 293 HEK cells transfected with either pCEP4(WT) or CFTR mutants (P3A, P2A, P740A, P750A, P759A) vectors were harvested and lysed following the procedure described previously (Xie et al., 1995, 1996). Login to comment
65 In experiments with WT, P3A, P2A, P740A, P750, and P759A, cis solution also contains 50 units/ml cAMP-dependent protein kinase A catalytic subunit. Login to comment
148 All three proline mutations are involved in the enhanced activity of the P3A CFTR channel To investigate which proline is critical for the increased open probability of the P3A channel, we constructed all three single proline mutants (P740A, P750A, P759A) and incorporated each of them into the planar lipid bilayer. Login to comment
150 Mutants P740A and P759A CFTR have similar open probability to WT CFTR, whereas P750A CFTR has significantly increased Po. Login to comment
154 P740A CFTR had Po similar to the wild type, while its mean open life time is significantly (p b0d; 0.05) lower (closing faster) than that of the WT CFTR, so FIGURE 4 ATPand PKA-dependent gating of the P3A CFTR channel. Login to comment
161 the P740A mutant must have a higher opening rate. Login to comment
198 The double (P2A; Fig. 10, lane 4) or single proline mutants (P740A, P750A, P759A; Fig. 10, lanes 5-7, respectively) were also fully glycosylated to a similar extent. Login to comment
231 The averaged values were Po afd; 0.204 afe; 0.036 (WT), 0.438 afe; 0.029 (WT af9; CyP (Cyclophilin A)), 0.577 afe; 0.090 (P3A CFTR), 0.161 afe; 0.018 (P740A), 0.426 afe; 0.030 (P750A), 0.166 afe; 0.034 (P759A), 0.272 afe; 0.059 (P2A), respectively. Login to comment
241 Lane 1 (UNT): untransfected 293 HEK cells; lane 2: WT CFTR expressing cells; lanes 3-7: P3A, P2A, P740A, P750A, and P759A CFTR expressing cells, respectively. Login to comment