ABCMdb

ABCA4 p.Gly1975Asp

ClinVar:	c.5923G>C , p.Gly1975Arg ? , not provided
Predicted by SNAP2:	A: D (59%), C: D (71%), D: D (95%), E: D (63%), F: D (80%), H: D (63%), I: D (75%), K: D (66%), L: D (80%), M: D (80%), N: N (53%), P: D (71%), Q: D (63%), R: D (95%), S: N (53%), T: N (53%), V: D (75%), W: D (91%), Y: D (80%),
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,

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Publications
[hide] The role of the photoreceptor ABC transporter ABCA... Biochim Biophys Acta. 2009 Jul;1791(7):573-83. Epub 2009 Feb 20. Molday RS, Zhong M, Quazi F
The role of the photoreceptor ABC transporter ABCA4 in lipid transport and Stargardt macular degeneration.
Biochim Biophys Acta. 2009 Jul;1791(7):573-83. Epub 2009 Feb 20., [PMID:19230850]

Abstract [show]
ABCA4 is a member of the ABCA subfamily of ATP binding cassette (ABC) transporters that is expressed in rod and cone photoreceptors of the vertebrate retina. ABCA4, also known as the Rim protein and ABCR, is a large 2,273 amino acid glycoprotein organized as two tandem halves, each containing a single membrane spanning segment followed sequentially by a large exocytoplasmic domain, a multispanning membrane domain and a nucleotide binding domain. Over 500 mutations in the gene encoding ABCA4 are associated with a spectrum of related autosomal recessive retinal degenerative diseases including Stargardt macular degeneration, cone-rod dystrophy and a subset of retinitis pigmentosa. Biochemical studies on the purified ABCA4 together with analysis of abca4 knockout mice and patients with Stargardt disease have implicated ABCA4 as a retinylidene-phosphatidylethanolamine transporter that facilitates the removal of potentially reactive retinal derivatives from photoreceptors following photoexcitation. Knowledge of the genetic and molecular basis for ABCA4 related retinal degenerative diseases is being used to develop rationale therapeutic treatments for this set of disorders.

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No. Sentence Comment
257 Some mutations affect only the retinal activated ATPase activity such as the G1975D and K1978M mutations in NBD2, whereas a large number of mutants affect both the basal and retinal stimulated ATPase activity of ABCA4 as exemplified by the L541P mutation in ECD1, T971N in NBD1 and E2096K in NBD2 [35]. Login to comment

[hide] Mechanistic studies of ABCR, the ABC transporter i... J Bioenerg Biomembr. 2001 Dec;33(6):523-30. Sun H, Nathans J
Mechanistic studies of ABCR, the ABC transporter in photoreceptor outer segments responsible for autosomal recessive Stargardt disease.
J Bioenerg Biomembr. 2001 Dec;33(6):523-30., [PMID:11804194]

Abstract [show]
ABCR is an ABC transporter that is found exclusively in vertebrate photoreceptor outer segments. Mutations in the human ABCR gene are responsible for autosomal recessive Stargardt disease, the most common cause of early onset macular degeneration. In this paper we review our recent work with purified and reconstituted ABCR derived from bovine retina and from cultured cells expressing wild type or site-directed mutants of human ABCR. These experiments implicate all-trans-retinal (or Schiff base adducts between all-trans-retinal and phosphatidylethanolamine) as the transport substrate, and they reveal asymmetric roles for the two nucleotide binding domains in the transport reaction. A model for the retinal transport reaction is presented which accounts for these experimental observations.

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106 (C) Synthetic substitutions of a conserved glycine in the Walker A motif of NBD-1 (G966D), NBD-2 (G1975D), or both (G966D/G1975D). Login to comment
114 When purified, reconstituted, and tested for ATPase activity, the synthetic mutations show (1) that mutations in NBD-1 (G966D or K969M), either alone or in combination with mutations in NBD-2 (G966D/G1975D or K969M/K1978M), abolish both basal and retinal-stimulated ATP hydrolysis and (2) that mutations in NBD-2 (G1975D or K1978M) do not alter the basal ATPase activity but lead to inhibition rather than stimulation of ATP hydrolysis by retinal (Fig. 4(C) and (D)), a pattern noted above for the naturally occurring NBD-2 mutations G1961E, G1977S, and E2096K. Login to comment