ABCMdb

PMID: 18776170

Vaughan AM, Tang C, Oram JF
ABCA1 mutants reveal an interdependency between lipid export function, apoA-I binding activity, and Janus kinase 2 activation.
J Lipid Res. 2009 Feb;50(2):285-92. Epub 2008 Sep 5., [PubMed]

Sentences

No. Mutations Sentence Comment

49 ABCA1 p.Trp590Ser ABCA1 p.Gln597Arg ABCA1 p.Cys1477Arg ABCA1 p.Arg587Trp ABCA1 p.Ala937Val ABCA1 p.Val399Ala ABCA1 p.Ile1517Arg the first extracellular loop (V399A, R587W, W590S, and Q597R), two were in the second extracellular loop (C1477R and I1517R), and one was in the Walker A motif of the first nucleotide binding domain (A937V, NBD1) (Fig. 1). Login to comment 50 ABCA1 p.Ala937Val ABCA1 p.Ala1950Val We also generated an artificial mutation in the Walker A motif of NBD2 (A1950V) that corresponds to the A937V mutation in NBD1. Login to comment 54 ABCA1 p.Gln597Arg The rank order of severity in impaired apoA-I-mediated cholesterol efflux was Q597R.A937V.R587W.C1477R.V399A.I1517R. Login to comment 55 ABCA1 p.Trp590Ser W590S.A1950V. Login to comment 82 ABCA1 p.Trp590Ser ABCA1 p.Ala1950Val This activation was nearly abolished in cells expressing all mutants except two (W590S and A1950V), which are the same two mutants that have the highest ability to cross-link apoA-I (Fig. 2E). Login to comment 92 ABCA1 p.Gln597Arg ABCA1 p.Ala937Val The two most severe mutations, which reduced apoA-I-mediated lipid efflux to less than 20% of normal, were located in the first extracellular loop (Q597R) and the ATP binding site (A937V). Login to comment 93 ABCA1 p.Gln597Arg ABCA1 p.Ala937Val ABCA1 p.Ala1950Val The two most severe mutations, which reduced apoA-I-mediated lipid efflux to less than 20% of normal, were located in the first extracellular loop (Q597R) and the ATP binding site (A937V). Login to comment 94 ABCA1 p.Ala1950Val Interestingly, the equivalent mutation in the ATP binding site of NBD2 (A1950V) had only a modest impairment of ABCA1 function, suggesting that the ATP binding activity of NBD1 is more critical for function than that of NBD2 or that these mutations have different effects on protein conformation. Login to comment 95 ABCA1 p.Trp590Ser ABCA1 p.Gln597Arg ABCA1 p.Cys1477Arg ABCA1 p.Arg587Trp Fitzgerald et al. (24) reported similar cell surface localizations for mutants R587W, W590S, Q597R, and C1477R. Login to comment 96 ABCA1 p.Trp590Ser ABCA1 p.Gln597Arg ABCA1 p.Gln597Arg ABCA1 p.Cys1477Arg ABCA1 p.Arg587Trp ABCA1 p.Arg587Trp Fitzgerald et al. (24) reported similar cell surface localizations for mutants R587W, W590S, Q597R, and C1477R. Login to comment 97 ABCA1 p.Gln597Arg ABCA1 p.Arg587Trp In contrast, Singaraja et al. (14) and Tanaka et al. (25) reported that ABCA1 with the R587W or Q597R mutations had impaired translocation to the plasma membrane in transfected cells. Login to comment 98 ABCA1 p.Gln597Arg Tanaka et al. (26) showed that endoplasmic reticulum stress can promote translocation of the Q597R ABCA1 mutant to the plasma membrane, where it still has impaired function, indicating that decreased trafficking alone cannot explain the dysfunctional effects of this mutation. Login to comment 99 ABCA1 p.Gln597Arg Tanaka et al. (26) showed that endoplasmic reticulum stress can promote translocation of the Q597R ABCA1 mutant to the plasma membrane, where it still has impaired function, indicating that decreased trafficking alone cannot explain the dysfunctional effects of this mutation. Login to comment 112 ABCA1 p.Trp590Ser Cholesterol and phospholipid efflux values for mutant W590S are labeled in panels A and B. Login to comment 113 ABCA1 p.Trp590Ser Cholesterol and phospholipid efflux values for mutant W590S are labeled in panels A and B. Login to comment 125 ABCA1 p.Trp590Ser A previous study showed that the W590S ABCA1 mutation severely impaired lipid efflux without affecting apoA-I cross-linking to ABCA1 (24), suggesting that apoA-I binding to ABCA1 can be dissociated from lipid export activity. Login to comment 126 ABCA1 p.Trp590Ser A previous study showed that the W590S ABCA1 mutation severely impaired lipid efflux without affecting apoA-I cross-linking to ABCA1 (24), suggesting that apoA-I binding to ABCA1 can be dissociated from lipid export activity. Login to comment 128 ABCA1 p.Trp590Ser The lipid export activity of the W590S ABCA1 mutant, however, was among the highest of the natural mutants, and thus values for cells expressing this mutant ABCA1 did not deviate far from the linear regression line when lipid transport activities were plotted against apoA-I/ABCA1 cross-linking (Fig. 4A, B). Login to comment 129 ABCA1 p.Trp590Ser The lipid export activity of the W590S ABCA1 mutant, however, was among the highest of the natural mutants, and thus values for cells expressing this mutant ABCA1 did not deviate far from the linear regression line when lipid transport activities were plotted against apoA-I/ABCA1 cross-linking (Fig. 4A, B). Login to comment 132 ABCA1 p.Trp590Ser The two ABCA1 mutants that had near-normal apoA-I-induced JAK2 activation were W590S Fig. 6. Login to comment 133 ABCA1 p.Trp590Ser The two ABCA1 mutants that had near-normal apoA-I-induced JAK2 activation were W590S Fig. 6. Login to comment 137 ABCA1 p.Ala1950Val and A1950V, which also had near-normal apoA-I cross-linking activity. Login to comment 138 ABCA1 p.Ala1950Val and A1950V, which also had near-normal apoA-I cross-linking activity. Login to comment