ABCMdb

ABCC7 p.Arg347Ile

ClinVar:	c.1039C>T , p.Arg347Cys ? , not provided c.1040G>A , p.Arg347His D , Pathogenic c.1040G>T , p.Arg347Leu D , Pathogenic c.1040G>C , p.Arg347Pro D , Pathogenic
CF databases:	c.1040G>C , p.Arg347Pro D , CF-causing ; CFTR1: This mutation destroys a Hha I restriciton site and creates an NcoI site and occurred in a family diagnosed as PS. The mutation have been identified and analyzed using the SSCP technique. c.1040G>A , p.Arg347His D , CF-causing ; CFTR1: The patient is of Italian origin and carries the [delta]F508 mutation on the other chromosome. Initially we thought this was the same mutation as R347 because it destroys the same hhai site; however, R347H does not create the NcoI site. c.1040G>T , p.Arg347Leu (CFTR1) D , A nucleotide change, G->T at position 1172, was detected leading to R347L. The other chromosome carries a [delta]F508. This mutation was found on one chromosome among 150 CF chromosomes screened. c.1039C>T , p.Arg347Cys (CFTR1) ? , This mutation was identified by DGGE and direct sequencing.
Predicted by SNAP2:	A: D (95%), C: D (95%), D: D (95%), E: D (95%), F: D (95%), G: D (95%), H: D (71%), I: D (95%), K: D (95%), L: D (80%), M: D (95%), N: D (95%), P: D (75%), Q: D (95%), S: D (95%), T: D (95%), V: D (95%), W: D (95%), Y: D (95%),
Predicted by PROVEAN:	A: N, C: D, D: D, E: N, F: D, G: D, H: N, I: D, K: N, L: N, M: N, N: N, P: N, Q: N, S: N, T: N, V: D, W: D, Y: D,

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Publications
[hide] Destabilization of the transmembrane domain induce... J Biol Chem. 2005 Feb 11;280(6):4968-74. Epub 2004 Nov 10. Choi MY, Partridge AW, Daniels C, Du K, Lukacs GL, Deber CM
Destabilization of the transmembrane domain induces misfolding in a phenotypic mutant of cystic fibrosis transmembrane conductance regulator.
J Biol Chem. 2005 Feb 11;280(6):4968-74. Epub 2004 Nov 10., 2005-02-11 [PMID:15537638]

Abstract [show]
Two phenotypic missense mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) channel pore (L346P and R347P in transmembrane (TM) segment 6) involve gain of a proline residue, but only L346P represents a significant loss of segment hydropathy. We show here that, for synthetic peptides corresponding to sequences of CFTR TM6 segments, circular dichroism spectra of wild type and R347P TM6 in membrane mimetic environments are virtually identical, but L346P loses approximately 50% helicity, implying a membrane insertion defect in the latter mutant. A similar defect was observed in the corresponding double-spanning ("hairpin") TM5/6-L346P synthetic peptide. Examination of the biogenesis of CFTR revealed that the full-length protein harboring the L346P mutation is rapidly degraded at the endoplasmic reticulum (ER), whereas the wild type and the R347P protein process normally. Furthermore, a second site mutation (R347I) that restores in vitro membrane insertion and folding of the TM5/6-L346P peptide also rescues the folding and cell surface chloride channel function of full-length L346P CFTR. The correlated in vitro/in vivo results demonstrate that destabilizing local hydrophobic character represents a sufficient signal for marking CFTR as a non-native protein by the ER quality control, with accompanying deleterious consequences to global protein folding events.

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No. Sentence Comment
4 Furthermore, a second site mutation (R347I) that restores in vitro membrane insertion and folding of the TM5/6-L346P peptide also rescues the folding and cell surface chloride channel function of full-length L346P CFTR. Login to comment
60 A, wild type sequence; B, TM5/6-L346P; C, TM5/6-R347P; and D, TM5/6-L346P-R347I. Login to comment
116 WT, L346P, R347P, L346P/R347I, and R347H CFTR expression was assayed by immunoblotting, using the mouse monoclonal anti-HA Ab. Login to comment
146 Consideration of amino acid replacements in the vicinity of the L346P mutation identified a second site mutation (R347I) that restored the hydrophobicity of the TM6 L346P-containing segment to the threshold level that ensured membrane insertion according to TM Finder (Fig. 1D) (26). Login to comment
147 The L346P/R347I single spanning TM6 peptide was first synthesized, and analysis of its CD spectrum confirmed that this mutation restored the ␣-helical content of this TM6 double mutant to its WT counterpart (Fig. 4A). Login to comment
148 We then assessed whether the R347I mutation could restore hairpin formation of the TM5/6-L346P polypeptide by the FRET assay. Login to comment
149 Using a TM5/6-L346P/R347I peptide in which a Trp residue was inserted near the C terminus (Table I), and in which the N terminus was labeled with a dansyl group, we found that the donor fluorescence quench in the double mutant was now similar to that of the WT TM5/6 (Fig. 4B). Login to comment
152 Immunoblot analysis demonstrated the appearance of the complex-glycosylated L346P/R347I CFTR in both transiently transfected COS-1 and stably transfected BHK cells, whereas no detectable amount of L346P CFTR was present (Figs. Login to comment
160 A, CD spectra of TM6-WT and TM6-L346P/R347I in LPC micelles. B, Trp fluorescence spectra for the unlabeled and labeled TM5/ 6-WT and TM5/6-L346P/R347I peptides in LPC micelles. FRET measurements were performed using peptides labeled with dansyl chloride as the acceptor fluorophore with the Trp residue in TM6 serving as a donor fluorophore. Login to comment
186 B, cAMP-stimulated iodide efflux of BHK cells expressing wild-type (wt), L346P, or L346P/ R347I CFTR. Login to comment
200 The partial reversion of the L346P CFTR processing defect by a second site mutation (R347I) (Fig. 3B), which restores full-length TM6 insertion potential (Fig. 1D), suggests that segment hydrophobicity is prominent among the factors that play determining roles in the post-translational folding of CFTR. Login to comment
212 Note that this salt bridge would similarly be abolished in the L346P/R347I mutant, perhaps explaining, in part, why this "rescue mutant" is not fully functional. Login to comment

[hide] Misfolding of the cystic fibrosis transmembrane co... Biochemistry. 2008 Feb 12;47(6):1465-73. Epub 2008 Jan 15. Cheung JC, Deber CM
Misfolding of the cystic fibrosis transmembrane conductance regulator and disease.
Biochemistry. 2008 Feb 12;47(6):1465-73. Epub 2008 Jan 15., 2008-02-12 [PMID:18193900]

Abstract [show]
Understanding the structural basis for defects in protein function that underlie protein-based genetic diseases is the fundamental requirement for development of therapies. This situation is epitomized by the cystic fibrosis transmembrane conductance regulator (CFTR)-the gene product known to be defective in CF patients-that appears particularly susceptible to misfolding when its biogenesis is hampered by mutations at critical loci. While the primary CF-related defect in CFTR has been localized to deletion of nucleotide binding fold (NBD1) residue Phe508, an increasing number of mutations (now ca. 1,500) are being associated with CF disease of varying severity. Hundreds of these mutations occur in the CFTR transmembrane domain, the site of the protein's chloride channel. This report summarizes our current knowledge on how mutation-dependent misfolding of the CFTR protein is recognized on the cellular level; how specific types of mutations can contribute to the misfolding process; and describes experimental approaches to detecting and elucidating the structural consequences of CF-phenotypic mutations.

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Sentences [show]
No. Sentence Comment
115 WT, L346P, R347P, L346P/R347I, and R347H CFTR expression was assayed by immunoblotting, using the mouse monoclonal anti-HA Ab. Equal loading of proteins was verified by visualizing the Na+/K+-ATPase (lower panel). Login to comment
138 The defect could be rescued in part by restoring hydrophobicity to TM6 via the double mutant L346P/R347I (Figure 4B). Login to comment