ABCC7 p.Lys1284Cys
| Predicted by SNAP2: | A: N (53%), C: N (66%), D: D (75%), E: D (66%), F: D (66%), G: D (63%), H: N (61%), I: D (59%), L: D (53%), M: D (53%), N: N (53%), P: D (71%), Q: N (82%), R: N (61%), S: N (82%), T: N (61%), V: N (57%), W: D (75%), Y: D (66%), |
| Predicted by PROVEAN: | A: N, C: D, D: N, E: N, F: D, G: D, H: N, I: D, L: D, M: N, N: N, P: N, Q: N, R: N, S: N, T: N, V: D, W: D, Y: D, |
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[hide] Phenylalanine-508 mediates a cytoplasmic-membrane ... Proc Natl Acad Sci U S A. 2008 Mar 4;105(9):3256-61. Epub 2008 Feb 27. Serohijos AW, Hegedus T, Aleksandrov AA, He L, Cui L, Dokholyan NV, Riordan JR
Phenylalanine-508 mediates a cytoplasmic-membrane domain contact in the CFTR 3D structure crucial to assembly and channel function.
Proc Natl Acad Sci U S A. 2008 Mar 4;105(9):3256-61. Epub 2008 Feb 27., 2008-03-04 [PMID:18305154]
Abstract [show]
Deletion of phenylalanine-508 (Phe-508) from the N-terminal nucleotide-binding domain (NBD1) of the cystic fibrosis transmembrane conductance regulator (CFTR), a member of the ATP-binding cassette (ABC) transporter family, disrupts both its folding and function and causes most cystic fibrosis. Most mutant nascent chains do not pass quality control in the ER, and those that do remain thermally unstable, only partially functional, and are rapidly endocytosed and degraded. Although the lack of the Phe-508 peptide backbone diminishes the NBD1 folding yield, the absence of the aromatic side chain is primarily responsible for defective CFTR assembly and channel gating. However, the site of interdomain contact by the side chain is unknown as is the high-resolution 3D structure of the complete protein. Here we present a 3D structure of CFTR, constructed by molecular modeling and supported biochemically, in which Phe-508 mediates a tertiary interaction between the surface of NBD1 and a cytoplasmic loop (CL4) in the C-terminal membrane-spanning domain (MSD2). This crucial cytoplasmic membrane interface, which is dynamically involved in regulation of channel gating, explains the known sensitivity of CFTR assembly to many disease-associated mutations in CL4 as well as NBD1 and provides a sharply focused target for small molecules to treat CF. In addition to identifying a key intramolecular site to be repaired therapeutically, our findings advance understanding of CFTR structure and function and provide a platform for focused biochemical studies of other features of this unique ABC ion channel.
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No. Sentence Comment
72 Cross-linking of C276/Q1280C and C276/K1284C confirms interaction of CL2 and NBD2.
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ABCC7 p.Lys1284Cys 18305154:72:38
status: NEW113 In fact, the Q1280C and K1284C substitutions in NBD2 of Cys-less CFTR containing the native Cys-276 residue in CL2 (illustrated in Fig. 3A, Top Right) enabled cross-linking by all MTS reagents tested.
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ABCC7 p.Lys1284Cys 18305154:113:24
status: NEW[hide] Restoration of domain folding and interdomain asse... FASEB J. 2010 Aug;24(8):3103-12. Epub 2010 Mar 16. He L, Aleksandrov LA, Cui L, Jensen TJ, Nesbitt KL, Riordan JR
Restoration of domain folding and interdomain assembly by second-site suppressors of the DeltaF508 mutation in CFTR.
FASEB J. 2010 Aug;24(8):3103-12. Epub 2010 Mar 16., [PMID:20233947]
Abstract [show]
Deletion of PHE508 (DeltaF508) from the first nucleotide-binding domain (NBD1) of CFTR, which causes most cystic fibrosis, disrupts the folding and assembly of the protein. Although the folding pathways and yield of isolated NBD1 are altered, its global structure is not, and details of the changes in the rest of the protein remain unclear. To gain further insight into how the whole mutant protein is altered, we have determined the influence of known second-site suppressor mutations in NBD1 on the conformation of this domain and key interfaces between domains. We found that the suppressors restored maturation of only those processing mutations located in NBD1, but not in other domains, including those in the C-terminal cytoplasmic loop of the second membrane-spanning domain, which forms an interface with the NBD1 surface. Nevertheless, the suppressors promoted the formation of this interface and others in the absence of F508. The suppressors restored maturation in a DeltaF508 construct from which NBD2 was absent but to a lesser extent than in the full-length, indicating that DeltaF508 disrupts interactions involving NBD2, as well as other domains. Rescue of DeltaF508-CFTR by suppressors required the biosynthesis of the entire full-length protein in continuity, as it did not occur when N- and C-terminal "halves" were coexpressed. Simultaneous with these interdomain perturbations, DeltaF508 resulted in suppressor reversed alterations in accessibility of residues both in the F508-containing NBD1 surface loop and in the Q loop within the domain core. Thus, in the context of the full-length protein, DeltaF508 mutation causes detectable changes in NBD1 conformation, as well as interdomain interactions.
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No. Sentence Comment
122 As shown in Fig. 3A, when ⌬F508 was introduced into Cys-less CFTR containing pairs 276C/Q1280C or 276C/K1284C at the NBD2/CL2 interface, no mature CFTR was detected, and neither M3M nor M8M (200 M) caused cross-linking of the immature band.
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ABCC7 p.Lys1284Cys 20233947:122:110
status: NEW125 As shown in Fig. 3A, ⌬F508-CFTR maturation was restored as was the cross-linking of the Cys pairs 276C/Q1280C and 276C/ K1284C at NBD2/CL2, as indicated by the slower migration rate of the mature bands in SDS-PAGE in samples treated with M3M and M8M (18).
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ABCC7 p.Lys1284Cys 20233947:125:127
status: NEW