ABCMdb

ABCA4 p.Thr506Ala

Predicted by SNAP2:	A: N (57%), C: N (53%), D: N (53%), E: N (61%), F: D (63%), G: N (53%), H: N (72%), I: N (53%), K: N (72%), L: D (53%), M: N (53%), N: N (72%), P: N (53%), Q: N (61%), R: N (61%), S: N (78%), V: N (57%), W: D (75%), Y: D (59%),
Predicted by PROVEAN:	A: N, C: D, D: D, E: D, F: D, G: D, H: D, I: N, K: D, L: N, M: N, N: D, P: D, Q: D, R: D, S: N, V: N, W: D, Y: D,

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Publications
[hide] Membrane topology of the ATP binding cassette tran... J Biol Chem. 2001 Jun 29;276(26):23539-46. Epub 2001 Apr 24. Bungert S, Molday LL, Molday RS
Membrane topology of the ATP binding cassette transporter ABCR and its relationship to ABC1 and related ABCA transporters: identification of N-linked glycosylation sites.
J Biol Chem. 2001 Jun 29;276(26):23539-46. Epub 2001 Apr 24., [PMID:11320094]

Abstract [show]
ABCR is a member of the ABCA subclass of ATP binding cassette transporters that is responsible for Stargardt macular disease and implicated in retinal transport across photoreceptor disc membranes. It consists of a single polypeptide chain arranged in two tandem halves, each having a multi-spanning membrane domain followed by a nucleotide binding domain. To delineate between several proposed membrane topological models, we have identified the exocytoplasmic (extracellular/lumen) N-linked glycosylation sites on ABCR. Using trypsin digestion, site-directed mutagenesis, concanavalin A binding, and endoglycosidase digestion, we show that ABCR contains eight glycosylation sites. Four sites reside in a 600-amino acid exocytoplasmic domain of the N-terminal half between the first transmembrane segment H1 and the first multi-spanning membrane domain, and four sites are in a 275-amino acid domain of the C half between transmembrane segment H7 and the second multi-spanning membrane domain. This leads to a model in which each half has a transmembrane segment followed by a large exocytoplasmic domain, a multi-spanning membrane domain, and a nucleotide binding domain. Other ABCA transporters, including ABC1 linked to Tangier disease, are proposed to have a similar membrane topology based on sequence similarity to ABCR. Studies also suggest that the N and C halves of ABCR are linked through disulfide bonds.

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No. Sentence Comment
58 ABCR(⌬8) had mutations in eight N-linked glycosylation sites within two ECDs at the following positions: Asn-98 (S100A), Asn-415 (T417A), Asn-444 (T446A), Asn-504 (T506A), Asn-1469 (T1471A), Asn-1529 (S1531A), Asn-1588 (S1590A), and Asn-1662 (T1664A) as shown in Fig. 2. Login to comment
79 (S100A), Asn-415 (T417A), Asn-444 (T446), and Asn-504 (T506A) were constructed as described above and are listed in Table I. The DNA sequences of all constructs were determined to verify the presence of the desired mutation and the absence of random mutations. Login to comment
153 TABLE I N-linked glycosylation mutants Protein N-Linked glycosylation sites Mutations ABCR(WT) Asn-98, Asn-415, Asn-444, Asn-504 None Asn-1469, Asn-1529, Asn-1588, Asn-1662 ABCR(⌬8) None S100A, T417A, T446A, T506A T1471A, S1531A, S1590A, T1664A ABCR(⌬4N) Asn-1469, Asn-1529, Asn-1588, Asn-1662 S100A, T417A, T446A, T506A ABCR(⌬4C) Asn-98, Asn-415, Asn-444, Asn-504 T1471A, S1531A, S1590A, T1664A ABCR(⌬7-N1469) Asn-1469 S100A, T417A, T446A, T506A T1471A, S1531A, S1590A S100A, T417A, T446A, T506A ABCR(⌬7-N1529) Asn-1529 T1471A, S1531A, T1664A S100A, T417A, T446A, T506A ABCR(⌬7-N1588) Asn-1588 T1471A, S1590A, T1664A ABCR(⌬7-N1662) Asn-1662 S100A, T417A, T446A, T506A S1531A, S1590A, T1664A N-tr-ABCR (WT) Asn-98, Asn-415, Asn-444, Asn-504 None N-tr-ABCR(⌬4) None S100A, T417A, T446A, T506A N-tr-ABCR(⌬3-N98) Asn-98 T417A, T446A, T506A N-tr-ABCR(⌬3-N415) Asn-415 S100A, T446A, T506A N-tr-ABCR(⌬3-N444) Asn-444 S100A, T417A, T506A N-tr-ABCR(⌬3-N504) Asn-504 S100A, T417A, T446A DISCUSSION Membrane Topology and Structural Features of ABCR- Computer-derived hydropathy profiles and comparative protein analysis serve as a useful starting point in developing working models for the topology of novel membrane proteins. Login to comment
57 ABCR(èc;8) had mutations in eight N-linked glycosylation sites within two ECDs at the following positions: Asn-98 (S100A), Asn-415 (T417A), Asn-444 (T446A), Asn-504 (T506A), Asn-1469 (T1471A), Asn-1529 (S1531A), Asn-1588 (S1590A), and Asn-1662 (T1664A) as shown in Fig. 2. Login to comment
78 (S100A), Asn-415 (T417A), Asn-444 (T446), and Asn-504 (T506A) were constructed as described above and are listed in Table I. The DNA sequences of all constructs were determined to verify the presence of the desired mutation and the absence of random mutations. Login to comment