ABCMdb

ABCA4 p.Leu1971Arg

ClinVar:	c.5912T>G , p.Leu1971Arg D , Pathogenic
Predicted by SNAP2:	A: D (63%), C: N (57%), D: D (75%), E: D (59%), F: N (57%), G: D (75%), H: D (53%), I: N (82%), K: D (63%), M: N (87%), N: D (66%), P: D (66%), Q: N (53%), R: D (95%), S: D (63%), T: N (57%), V: N (78%), W: D (71%), Y: N (53%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: N, K: D, M: N, N: D, P: D, Q: D, R: D, S: D, T: D, V: D, W: D, Y: D,

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Publications
[hide] Spectrum of ABCR gene mutations in autosomal reces... Eur J Hum Genet. 1998 May-Jun;6(3):291-5. Rozet JM, Gerber S, Souied E, Perrault I, Chatelin S, Ghazi I, Leowski C, Dufier JL, Munnich A, Kaplan J
Spectrum of ABCR gene mutations in autosomal recessive macular dystrophies.
Eur J Hum Genet. 1998 May-Jun;6(3):291-5., [PMID:9781034]

Abstract [show]
Stargardt disease (STGD) and late-onset fundus flavimaculatus (FFM) are autosomal recessive conditions leading to macular degenerations in childhood and adulthood, respectively. Recently, mutations of the photoreceptor cell-specific ATP binding transporter gene (ABCR) have been reported in Stargardt disease. Here, we report on the screening of the whole coding sequence of the ABCR gene in 40 unrelated STGD and 15 FFM families and we show that mutations truncating the ABCR protein consistently led to STGD. Conversely, all mutations identified in FFM were missense mutations affecting uncharged amino acids. These results provide the first genotype-phenotype correlations in ABCR gene mutations.

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No. Sentence Comment
45 Furthermore, all ABCR missense mutations Table 1 Mutations in the ABCR gene in STGD and FFM families Conserved aa in: Nucleotide change Amino acid change Domain ABCs RmP Phenotype Families Comment (571-2)A®G splicing mutation STGD 1 HAD1 (1938-2)A®G splicing mutation STGD 1 (4668+2)T®C splicing mutation STGD 1 (4735+2)T®A splicing mutation STGD 1 del(5196+1-5196+6 splicing mutation STGD 1 LOZ2 2570 delT frameshift mutation STGD 1 3209insGT frameshift mutation STGD 2 CHE2 G3754T E1252X STGD 1 C3994T Q1332X STGD 1 C6337G I2113X STGD 1 JEG2 C52T R18W IC - + STGD 1 C634T R212C EC - + STGD 5 GEN2, JEG2 G1908T Q636H IC - + STGD 1 LOZ2 C3056T T1019M IC - + STGD 1 C3322T R1107C IC - + STGD 1 JUL2 C4916T R1640W IC + + STGD 2 MAR1 G5929A G1977S ATP2 + + STGD 1 GEN2 G6320A R2107H IC + + STGD 1 JUL2 C3114T A1038V IC - + STGD 2 CHE2 +FFM +1 VII2 T1622C L541P EC - + FFM 1 VII2 T31C L11P IC + + FFM 1 G3272A G1090E IC + + FFM 1 G4522T G1508C IC + + FFM 1 C5908T L1970F IC + + FFM 1 GON2 T5912G L1971R IC + + FFM 1 GON2 Mutations refer to the standard nomenclature. Login to comment

[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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134 Disease mutations, which are substituted in Stargardt disease, are shown in red italics - NBD1 (N965S, T971N, A1038V, S1071V, E1087K, R1108C); NBD2 (G1961E, L1971R, G1977S, L2027F, R2038W, R2077W, R2106C, R2107H). Login to comment
225 A subset of missense mutations reside in NBD1 (N965S, T971N, A1038V, S1071V, E1087K, R1108C, R1129L) and NBD2 (G1961E, L1971R, G1977S, L2027F, R2038W, R2077W, R2106C, R2107H). Login to comment
226 Several of these, including N965S, T971N, E1087K, L1971R, G1977S, reside inside or close to the Walker A and B motifs [29,90,92,95,97,100,102]. Login to comment

[hide] Functional analysis of genetic mutations in nucleo... Biochemistry. 2003 Sep 16;42(36):10683-96. Biswas-Fiss EE
Functional analysis of genetic mutations in nucleotide binding domain 2 of the human retina specific ABC transporter.
Biochemistry. 2003 Sep 16;42(36):10683-96., [PMID:12962493]

Abstract [show]
The rod outer segment (ROS) ABC transporter (ABCR) plays an important role in the outer segment of retinal rod cells, where it functions as a transporter of all-trans retinal, most probably as the complex lipid, retinylidene-phosphatidyl-ethanolamine. We report here a quantitative analysis of the structural and functional effects of genetic mutations, associated with several macular degenerations, in the second nucleotide-binding domain of ABCR (NBD2). We have analyzed the ATP binding, kinetics of ATP hydrolysis, and structural changes. The results of these multifaceted analyses were correlated with the disease severity and prognosis. Results presented here demonstrated that, in wild type NBD2, distinct conformational changes accompany nucleotide (ATP and ADP) binding. Upon ATP binding, NBD2 protein changed to a relaxed conformation where tryptophans became more solvent-exposed, while ADP binding reverses this process and leads back to a taut conformation that is also observed with the unbound protein. This sequence of conformational change appears to be important in the energetics of the ATP hydrolysis and may have important structural consequences in the ability of the NBD2 domain to act as a regulator of the nucleotide-binding domain 1. Some of the mutant proteins displayed strikingly different patterns of conformational changes upon nucleotide binding that pointed to unique structural consequences of these genetic mutations. The ABCR dysfunctions, associated with various retinopathies, are multifaceted in nature and include alterations in protein structure as well as the attenuation of ATPase activity and nucleotide binding.

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No. Sentence Comment
73 The NBD2 expression vector pET29aNBD2 was used as template, 12 cycles of PCR, and each cycle was 30 s at 95 °C, 30 s at 50 °C, and 15 min at 68°C using complimentary oligonucleotides to produce the mutations L1971R, R2038W, G2146D, K2175A, and D2177N. Login to comment
74 The primers used for mutagenesis were as follows: L1971R, CGC CCT GGA GAG TGC TTT GGC CTC CGG GGA GTG AAT GGT GCC GGC AAA AC; R2038W, CTT TAC CTT TAT GCC AGG CTT CGA GGT GTA CCA GC, G2146D, CTG GCC ATC ATG GTA AAG GAC GCC TTT CGA TGT AT; D2177N, ATC AAA TCC CCG AAG GAC AAC CTG CTT CCT GAC CTG AAC; K2175A, CA ATG AAG ATC AAA TCC CCG GCG GAC GAC CTG CTT CCT GA. All of the mutations were disease-associated with the exception of K2175A. Login to comment
103 The locations of the disease associated mutations investigated in this study; L1971R, R2038W, G2146D, L2027F, and D2177N are indicated. Login to comment
144 Here, we have used site-specific mutagenesis to create disease-related genetic mutations: L1971R, D2177N, L2027F, R2038W, and G2146D as well as a synthetic mutation, K2175A. Login to comment
153 Lane 1: protein molecular weight standards; lane 2, wild-type NBD2; lane 3, L2027F mutant; lane 4, L1971R mutant; lane 5, D2177N; lane 6, G2146D; lane 7, R2038W mutant; lane 8, K2175A. Login to comment
168 The amino acid change, L1971R, is associated with mild to moderate forms of macular degeneration (Fundus flavimaculatus) (24). Login to comment
169 Analysis of NBD2 polypeptides harboring this mutation demonstrated that its effect on ATP hydrolysis was significant (i.e., a 57% decrease in specific activity with respect to the wild type control), and the observed rates of hydrolysis for L1971R (72 nmol/min/mg) were attenuated in comparison to the wild-type NBD2 (Figure 5, Table 1). Login to comment
225 The binding affinity of mutant L1971R decreased approximately 4-fold from that of the wild type and Kd was determined to be 2.1 × 10-6 M (Figure 6A). Login to comment
253 The curves represent a least squares nonlinear regression curve fit of the data representing the (A) L1971R mutant, (B) D2177N mutant, (C) G2146D mutant, (D) R2038W mutant, and (E) K2175A mutant. Login to comment
259 We observed only slight differences in the quenching profile of the L1971R mutant, both in the presence and in the absence of nucleotide binding (Figure 7B, Table 1). Login to comment
260 The L1971R mutation is associated with a "milder form" of macular degeneration, Fundus Flavimaculatus. Login to comment
261 The L1971R mutant was observed to have a reduced rate of ATP hydrolysis, 62% that of the wild type. Login to comment
267 Stern Volmer plots of the (A) wild-type NBD2, (B) L1971R mutant, (C) L2027F mutant, (D) D2177N mutant, (E) R2038W mutant, (F) G2146D mutant, and (F) K2175A mutant. Login to comment
303 The mutation L1971R has been identified with individuals suffering from the milder form of macular degeneration, Fundus Flavimaculatus, while G2146D and R2038W are associated with STGD1 and CRD, both of which are more severe forms of degeneration. Login to comment
305 In this study, the mutations R2038W, L1971R and G2146D led to comparable (~50%) decreases in ATP hydrolysis relative to the wild-type control. Login to comment
347 In the case of L1971R, dramatic changes in the quenching profiles between the wild type and mutant protein were not observed. Login to comment
348 The rate of ATP hydrolysis for L1971R was 62% of that observed for NBD2 wild type. Login to comment
352 Although L1971R was associated with a 62% decrease in ATP hydrolysis as compared to the wild type control, it was not significantly affected in terms of its structural response to nucleotide binding. 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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No. Sentence Comment
109 Among the variants tested in NBD-2, L1971R eliminates both basal and retinal-stimulated ATP hydrolysis, whereas G1977S and E2096K resemble G1961E in showing inhibition rather than stimulation of ATPase by retinal. Login to comment
110 The complete or nearly complete elimination of all ATPase activity produced by single NBD mutations-T971N, A1038V, or L1971R-implies that the two NBDs are allosterically coupled. Login to comment