Human transporters associated with antigen processing possess a promiscuous peptide-binding site.
The peptide selectivity of the human transporters associated with antigen processing (TAP) was investigated using a panel of peptides of varying length and sequence. Peptides were assayed for their ability to compete for the translocation of a labeled reporter peptide containing an N-linked glycosylation acceptor site in Streptolysin O (SLO)-permeabilized cells. We find that human TAP is very promiscuous for peptides in the 8-12 amino acid range, while showing increased selectivity and lower translocation efficiency for peptides in the 13-30 amino acid range. The minimum peptide length appears to be 8 amino acids, while the maximum length appears to be approximately 25 amino acids. Furthermore, a photoactive peptide analogue was synthesized that can photolabel TAP molecules. Using this analogue, we showed that an ATP-independent peptide-binding site exists on TAP, and that competition for translocation reflects competition for peptide binding.
Androlewicz
M J
MJ
Section of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06510.
Cresswell
P
P
D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D017951:Antigen Presentation; D001665:Binding Sites; D001667:Binding, Competitive; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D015395:Histocompatibility Antigens Class I / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000235:genetics / Q000378:metabolism
D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D018528:ATP-Binding Cassette Transporters; D002352:Carrier Proteins; D015395:Histocompatibility Antigens Class I; D009842:Oligopeptides; C073119:TAP1 protein, human; D000255:Adenosine Triphosphate