Gileadi U, Higgins C F
Nuffield Department of Clinical Biochemistry and Imperial Cancer Research Fund Laboratories, Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom.
J Biol Chem. 1997 Apr 25;272(17):11103-8. doi: 10.1074/jbc.272.17.11103.
The ATP-binding cassette transporters associated with antigen presentation (Tap1 and Tap2) mediate the transport of peptide fragments across the endoplasmic reticulum membrane of mammalian cells. Tap1 and Tap2 are closely related to one another and are believed to function as a heterodimer. Each protein possesses a hydrophobic domain predicted to span the membrane multiple times and a highly conserved nucleotide-binding domain. We have assessed the transmembrane topology of Tap1 by expressing a series of fusions to a reporter protein, the mature form of beta-lactamase in Escherichia coli. From these data a topological model can be derived in which Tap1 spans the membrane eight times, with several large loops exposed in the lumen of the endoplasmic reticulum and with both the N and C termini (including the nucelotide-binding domain) residing in the cytoplasm.
与抗原呈递相关的ATP结合盒转运体（Tap1和Tap2）介导肽片段跨哺乳动物细胞内质网膜的转运。Tap1和Tap2彼此密切相关，被认为以异源二聚体形式发挥作用。每种蛋白质都具有预计多次跨膜的疏水域和高度保守的核苷酸结合域。我们通过在大肠杆菌中表达一系列与报告蛋白（β-内酰胺酶成熟形式）的融合蛋白来评估Tap1的跨膜拓扑结构。根据这些数据可以得出一个拓扑模型，其中Tap1跨膜八次，在内质网腔中有几个大环暴露在外，N端和C端（包括核苷酸结合域）都位于细胞质中。
