ABCC4 p.Gly538Asp
| Predicted by SNAP2: | A: D (80%), C: D (80%), D: D (91%), E: D (95%), F: D (91%), H: D (91%), I: D (91%), K: D (95%), L: D (91%), M: D (91%), N: D (85%), P: D (91%), Q: D (91%), R: D (95%), S: D (75%), T: D (91%), V: D (91%), W: D (95%), Y: D (91%), |
| Predicted by PROVEAN: | A: D, C: D, D: D, E: D, F: D, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, S: D, T: D, V: D, W: D, Y: D, |
[switch to compact view]
Comments [show]
None has been submitted yet.
[hide] The human multidrug resistance protein 4 (MRP4, AB... J Pharmacol Exp Ther. 2008 Jun;325(3):859-68. Epub 2008 Mar 25. Abla N, Chinn LW, Nakamura T, Liu L, Huang CC, Johns SJ, Kawamoto M, Stryke D, Taylor TR, Ferrin TE, Giacomini KM, Kroetz DL
The human multidrug resistance protein 4 (MRP4, ABCC4): functional analysis of a highly polymorphic gene.
J Pharmacol Exp Ther. 2008 Jun;325(3):859-68. Epub 2008 Mar 25., [PMID:18364470]
Abstract [show]
ABCC4 encodes multidrug resistance protein 4 (MRP4), a member of the ATP-binding cassette family of membrane transporters involved in the efflux of endogenous and xenobiotic molecules. The aims of this study were to identify single nucleotide polymorphisms of ABCC4 and to functionally characterize selected nonsynonymous variants. Resequencing was performed in a large ethnically diverse population. Ten nonsynonymous variants were selected for analysis of transport function based on allele frequencies and evolutionary conservation. The reference and variant MRP4 cDNAs were constructed by site-directed mutagenesis and transiently transfected into human embryonic kidney cells (HEK 293T). The function of MRP4 variants was compared by measuring the intracellular accumulation of two antiviral agents, azidothymidine (AZT) and adefovir (PMEA). A total of 98 variants were identified in the coding and flanking intronic regions of ABCC4. Of these, 43 variants are in the coding region, and 22 are nonsynonymous. In a functional screen of ten variants, there was no evidence for a complete loss of function allele. However, two variants (G187W and G487E) showed a significantly reduced function compared to reference with both substrates, as evidenced by higher intracellular accumulation of AZT and PMEA compared to the reference MRP4 (43 and 69% increase in accumulation for G187W compared with the reference MRP4, with AZT and PMEA, respectively). The G187W variant also showed decreased expression following transient transfection of HEK 293T cells. Further studies are required to assess the clinical significance of this altered function and expression and to evaluate substrate specificity of this functional change.
Comments [show]
None has been submitted yet.
No. Sentence Comment
89 This mutant, G538D, has an aspartate instead of a glycine at the fourth position in the ABC signature of the first nucleotide binding domain (NBD; Fig. 1).
X
ABCC4 p.Gly538Asp 18364470:89:13
status: NEW110 Initially, ABCC4 haplotypes were inferred from all variable sites with a frequency higher than TABLE 1 Primers used for constructing the variants and the nonfunctional mutant by site-directed mutagenesis Variant Sequencea (5Ј-3Ј) P78A F: GAATGACGCACAGAAGGCTTCTTTAACAAGAGC R: GCTCTTGTTAAAGAAGCCTTCTGTGCGTCATTC G187W F: GTAACATGGCCATGTGGAAGACAACCACAG R: CTGTGGTTGTCTTCCACATGGCCATGTTAC K293E F: GTACGCCTGGGAAGAGTCATTTTCAAATC R: GATTTGAAAATGACTCTTCCCAGGCGTAC K304N F: CCAATTTGAGAAATAAGGAGATTTCCAAG R: CTTGGAAATCTCCTTATTTCTCAAATTGG P403L F: GCGCAACCGTCAGCTGCTGTCAGATGGTAAAAAG R: CTTTTTACCATCTGACAGCAGCTGACGGTTGCGC G487E F: CCCTGGGTGTTCTCGGAAACTCTGAGGAG R: CTCCTCAGAGTTTCCGAGAACACCCAGGG K498E F: GTAATATTTTATTTGGGAAGGAATACGAAAAGG R: CCTTTTCGTATTCCTTCCCAAATAAAATATTAC M744V F: GGGCAAACAAACAAAGTGTGCTAAATGTCACTG R: CAGTGACATTTAGCACACTTTGTTTGTTTGCCC C956S F: CGTCTGGATGCCATCTCTGCCATGTTTGTCATC R: GATGACAAACATGGCAGAGATGGCATCCAGACG V1071I F: CACAAGAAAAGATTGGCATTGTGGGAAG R: CTTCCCACAATGCCAATCTTTTCTTGTG G538D F: GGAACCACGCTGAGTGGAGACCAGAAAGCACGGGTAAACC R: GGTTTACCCGTGCTTTCTGGTCTCCACTCAGCGTGGTTCC F, forward; R, reverse.
X
ABCC4 p.Gly538Asp 18364470:110:1004
status: NEW140 This is illustrated by the fact that the accumulation of both substrates in the cells transfected with the G538D construct is not statistically different from the vector-transfected cells (Fig. 4A).
X
ABCC4 p.Gly538Asp 18364470:140:107
status: NEW179 To check that the functional differences were not due to differences in localization of the variants at the cell membrane, immunocytochemistry studies were carried out with the less functional variants (G187W, G487E, and P78A), the nonfunctional mutant (G538D) and the more functional variant (C956S).
X
ABCC4 p.Gly538Asp 18364470:179:254
status: NEW240 C, P78A; D, G187W; E, P403L; F, G487E; G, C956S; H, G538D.
X
ABCC4 p.Gly538Asp 18364470:240:52
status: NEW