ABCMdb

PMID: 21796426

Holstead RG, Li MS, Linsdell P
Functional Differences in Pore Properties Between Wild-Type and Cysteine-Less Forms of the CFTR Chloride Channel.
J Membr Biol. 2011 Oct;243(1-3):15-23. Epub 2011 Jul 28., [PubMed]

Sentences

No. Mutations Sentence Comment

3 ABCC7 p.Cys343Ser Our results suggest that the conductance difference is the result of a single substitution, of C343: the point mutant C343S has a conductance similar to cys-less, whereas the reverse mutation, S343C in a cys-less background, restores wild-type conductance levels. Login to comment 4 ABCC7 p.Cys225Ser ABCC7 p.Cys866Ser ABCC7 p.Cys128Ser Other cysteine substitutions (C128S, C225S, C376S, C866S) were without effect. Login to comment 26 ABCC7 p.Val510Ala Cys-less CFTR also included a mutation in the first NBD (V510A) to increase protein expression in the cell membrane (Li et al. 2009). Login to comment 27 ABCC7 p.Val510Ala ABCC7 p.Val510Ala The V510A mutation itself is not expected to affect single-channel conductance, which has previously been reported to be similarly increased in cys-less CFTR without (Cui et al. 2006; Mense et al. 2006) and with (Li et al. 2009; Bai et al. 2010) the V510A mutation. Login to comment 56 ABCC7 p.Cys343Ser Single-channel conductance was also significantly increased in the point mutant C343S (P \ 0.0001) (Fig. 2), albeit to a slightly lesser degree than in cys-less (14.5 ± 2.7%, n = 8). Login to comment 57 ABCC7 p.Cys343Ser In fact, the conductances of cys-less and C343S were not significantly different (P [ 0.4). Login to comment 58 ABCC7 p.Cys276Ser ABCC7 p.Cys225Ser ABCC7 p.Cys866Ser ABCC7 p.Cys128Ser In contrast, other point mutants studied (C128S, C225S, C276S, C866S) had conductances that were not significantly different from wild type but were significantly different from cys-less (Fig. 2d). Login to comment 67 ABCC7 p.Cys343Ser ABCC7 p.Cys343Val ABCC7 p.Cys343Leu ABCC7 p.Cys343Thr ABCC7 p.Cys343Ala As shown in Fig. 3, single-channel conductance was significantly reduced in C343L, significantly increased in C343A as well as C343S and not significantly changed in C343T and C343V. Login to comment 82 ABCC7 p.Cys343Ser b, c Mean single channel I-V relationships recorded under these conditions for wild-type (filled circle, b), cys-less (open circle, b), C343S (filled circle, c) and cys-less S343C (open circle, c). Login to comment 87 ABCC7 p.Cys343Leu ABCC7 p.Cys343Ala b Mean single channel I-V relationships recorded under these conditions for C343A (filled circle) and C343L (open circle). Login to comment 122 ABCC7 p.Cys343Ser Thus, the point mutation C343S causes an increase in conductance to a near cys-less level, whereas the revertant mutation S343C in a cys-less background reduces conductance to a near wild-type level (Fig. 2). Login to comment 138 ABCC7 p.Cys343Ser ABCC7 p.Cys343Thr Since C343T (unlike C343S) was not associated with a significant change in single-channel conductance (Fig. 3), a cys-less construct in which C343 is replaced by threonine, rather than serine, might be considered to retain wild-type channel properties more faithfully. Login to comment 139 ABCC7 p.Cys343Ser However, since most other permeation properties of cys-less were found to be indistinguishable between wild-type and cys-less (containing the C343S mutation), it seems likely that in most respects it is functionally inconsequential if this site is a cysteine, serine or threonine. Login to comment