title: Substrate specificity of allelic variants of the TAP peptide transporter.
abstract: The transporter associated with antigen processing (TAP) translocates peptides from the cytosol into the lumen of the endoplasmic reticulum (ER). An important determinant for the specificity of translocation is the identity of the C-terminal residue of the peptide substrate. In the rat, a suitable C terminus is necessary but not always sufficient for a peptide to be selected for translocation. Here we show that sequence constraints within a peptide of optimal length (9 residues) may interfere with transport; that the transporter selectively translocates shorter derivatives of a 16-mer peptide rather than the 16-mer itself; and that the transporter cimb allele, which is most selective in the C termini it will tolerate, is more relaxed in peptide length preference than is the clma variant.
authors.affiliation: Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139.
authors.forename: M T
authors.initials: MT
authors.lastname: Heemels
authors.forename: H L
authors.initials: HL
authors.lastname: Ploegh
mesh_terms: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D001692:Biological Transport; D008099:Liver / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism*; D008969:Molecular Sequence Data; D051381:Rats; D011916:Rats, Inbred F344; D011917:Rats, Inbred Lew; D017421:Sequence Analysis; D013379:Substrate Specificity
chemical_list: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters; C073119:TAP1 protein, human; C486172:Tap1 protein, rat; C489514:Tap2 protein, rat; C071692:TAP2 protein, human