ABCMdb

ABCC7 p.Ala204Leu

Predicted by SNAP2:	C: D (59%), D: D (80%), E: D (80%), F: D (80%), G: N (87%), H: D (85%), I: D (71%), K: D (75%), L: D (66%), M: D (71%), N: D (59%), P: D (71%), Q: D (75%), R: D (85%), S: N (78%), T: N (82%), V: N (57%), W: D (85%), Y: D (71%),
Predicted by PROVEAN:	C: D, D: D, E: D, F: D, G: N, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, S: N, T: N, V: N, W: D, Y: D,

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Publications
[hide] Detergent binding explains anomalous SDS-PAGE migr... Proc Natl Acad Sci U S A. 2009 Feb 10;106(6):1760-5. Epub 2009 Jan 30. Rath A, Glibowicka M, Nadeau VG, Chen G, Deber CM
Detergent binding explains anomalous SDS-PAGE migration of membrane proteins.
Proc Natl Acad Sci U S A. 2009 Feb 10;106(6):1760-5. Epub 2009 Jan 30., 2009-02-10 [PMID:19181854]

Abstract [show]
Migration on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) that does not correlate with formula molecular weights, termed "gel shifting," appears to be common for membrane proteins but has yet to be conclusively explained. In the present work, we investigate the anomalous gel mobility of helical membrane proteins using a library of wild-type and mutant helix-loop-helix ("hairpin") sequences derived from transmembrane segments 3 and 4 of the human cystic fibrosis transmembrane conductance regulator (CFTR), including disease-phenotypic residue substitutions. We find that these hairpins migrate at rates of -10% to +30% vs. their actual formula weights on SDS-PAGE and load detergent at ratios ranging from 3.4-10 g SDS/g protein. We additionally demonstrate that mutant gel shifts strongly correlate with changes in hairpin SDS loading capacity (R(2) = 0.8), and with hairpin helicity (R(2) = 0.9), indicating that gel shift behavior originates in altered detergent binding. In some cases, this differential solvation by SDS may result from replacing protein-detergent contacts with protein-protein contacts, implying that detergent binding and folding are intimately linked. The CF-phenotypic V232D mutant included in our library may thus disrupt CFTR function via altered protein-lipid interactions. The observed interdependence between hairpin migration, SDS aggregation number, and conformation additionally suggests that detergent binding may provide a rapid and economical screen for identifying membrane proteins with robust tertiary and/or quaternary structures.

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No. Sentence Comment
45 Five mutants (A204L, P205A/ Table 1. Login to comment
85 Gel shifts, SDS binding, helicity, and column MW of TM3/4 hairpins Hairpin* Gel shift (dMW, %) Bound SDS (g/g) Helicity (MRE X 103)† Column MW (mut-wt, %)‡ V232Dcf -11 Ϯ 2.6 3.4 Ϯ 0.9 -17 Ϯ 1.2 ϩ19 Ϯ 1.5 V232K -10 Ϯ 3.0 3.8 Ϯ 0.6 -16 Ϯ 1.1 ϩ5.6 Ϯ 1.6 A204L -2.2 Ϯ 2.3 6.0 Ϯ 0.7 -18 Ϯ 1.3 ϩ3.4 Ϯ 1.6 P205A/V232Dcf ϩ0.12 Ϯ 5.2 4.7 Ϯ 0.4 -19 Ϯ 2.6 ϩ21 Ϯ 0.6 WT ϩ0.42 Ϯ 4.5 5.4 Ϯ 1.4 -18 Ϯ 2.2 0.0 Ϯ 0.79 V232A ϩ3.6 Ϯ 3.7 5.2 Ϯ 0.4 -18 Ϯ 0.9 ϩ6.1 Ϯ 1.9 P205Scf ϩ4.7 Ϯ 6.0 4.7 Ϯ 1.0 -18 Ϯ 0.7 ϩ4.4 Ϯ 1.6 Q220W ϩ6.3 Ϯ 2.4 5.0 Ϯ 0.7 -21 Ϯ 2.7 -4.9 Ϯ 1.3 G228L ϩ14 Ϯ 5.1 6.9 Ϯ 1.4 -23 Ϯ 1.7 ϩ14 Ϯ 2.6 E217V ϩ28 Ϯ 1.3 6.7 Ϯ 1.0 -25 Ϯ 1.7 ϩ32 Ϯ 4.0 E217F ϩ29 Ϯ 2.8 9.4 Ϯ 1.9 -28 Ϯ 2.6 ϩ17 Ϯ 1.1 E217S/S222E ϩ29 Ϯ 7.6 10 Ϯ 2.3 -25 Ϯ 2.8 ϩ35 Ϯ 0.9 Glycophorin§ - 3.4 Ϯ 0.6 -9.5 Ϯ 1.2 ϩ83 Ϯ 5.1 *Mutant hairpins are listed in order of increasing gel shift. Login to comment

[hide] Sequence hydropathy dominates membrane protein res... Biochemistry. 2012 Aug 7;51(31):6228-37. Epub 2012 Jul 25. Nadeau VG, Rath A, Deber CM
Sequence hydropathy dominates membrane protein response to detergent solubilization.
Biochemistry. 2012 Aug 7;51(31):6228-37. Epub 2012 Jul 25., [PMID:22779403]

Abstract [show]
The ability to predict from amino acid sequence how membrane protein structures will respond to detergent solubilization would significantly facilitate experimental characterization of these molecules. Here we have investigated and compared the response to solubilization by the "mild" n-dodecyl-beta-d-maltoside (DDM) and "harsh" sodium dodecyl sulfate (SDS) of wild-type and point mutant "hairpin" (helix-loop-helix) membrane proteins derived from the third and fourth TM segments of the human cystic fibrosis transmembrane conductance regulator (CFTR) and the intervening extracellular loop. Circular dichroism spectroscopy, size-exclusion chromatography, and pyrene fluorescence spectroscopy were used to evaluate the secondary structures, hairpin-detergent complex excluded volumes, and hairpin compactness of the detergent-solubilized sequences. Sequence hydrophobicity is found to be the dominant factor dictating membrane protein response to detergent solubilization by DDM and SDS, with hairpin secondary structure exquisitely sensitive to mutation when DDM is used for solubilization. DDM and SDS differ principally in their ability to promote approach of TM segment ends, although hairpin compactness remains sensitive to point mutations. Our overall findings suggest that protein-protein and protein-detergent interactions are determined concomitantly, with the net hydropathy of residues exposed to detergent dominating the observed properties of the solubilized protein.

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No. Sentence Comment
89 We further noted that the spectra of mutant hairpins solubilized in DDM exhibited a gradation of intensities, whereas SDS-solubilized mutant spectra could be divided into "low helicity" (WT, V232D, A204L, and P205S) or "high helicity" (E217V, ES/SE, and E217F) clusters. Login to comment
144 In DDM (Figure 4B, left), we found that the P205S (E:M = 0.87 ± 0.20), E217V (E:M = 0.78 ± 0.06), E271F (E:M = 0.76 ± 0.12) and A204L spectra (E:M = 0.69 ± 0.02) each displayed excimer fluorescence, and the E:M ratio of each of these "compact" mutants was statistically distinct from the negative control in DDM (E:M = 0.52 ± 0.02, 4.7 × 10-6 ≤ p ≤ 0.008). Login to comment
146 In contrast, after SDS solubilization (Figure 4B, right), excimer emission above negative control (E:M = 0.21 ± 0.004) levels was present only in the A204L mutant (E:M = 0.32 ± 0.06, p = 0.027); the E217V mutant had an E:M ratio higher than the negative control, but this difference was of marginal significance (E:M = 0.28 ± 0.04, p = 0.062). Login to comment
189 We were thus excited to observe that solubilization by DDM supports a distance <10 Å between pyrene molecules conjugated at the ends of TM3 and TM4, giving rise to a subset of "compact" mutants (P205S, E217V, E217F, and A204L) (Figure 4B, left). Login to comment