Peptide length and sequence specificity of the mouse TAP1/TAP2 translocator

• Published in: The Journal of experimental medicine Vol. 179; no. 2; pp. 533 - 540
• Main Authors: SCHUMACHER, T. N. M, KANTESARIA, D. V, HEEMELS, M.-T, ASHTON-RICKARDT, P. G, SHEPHERD, J. C, FRUH, K, YOUNG YANG, PETERSON, P. A, TONEGAWA, S, PLOEGH, H. L
• Format: Journal Article
• Language: English
• Published: New York, NY Rockefeller University Press 01.02.1994; The Rockefeller University Press
• Subjects: Adenosine Triphosphate - metabolism; Amino Acid Sequence; Animals; Antigen-antibody reactions, antigen-antibody complexes, antibody-complement and others. Study of affinity. Antigen presentation; ATP Binding Cassette Transporter, Subfamily B, Member 2; ATP Binding Cassette Transporter, Subfamily B, Member 3; ATP-Binding Cassette Transporters; Binding, Competitive; Biological and medical sciences; Biological Transport; Carrier Proteins - metabolism; Female; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Histocompatibility Antigens Class II - metabolism; Mice; Mice, Inbred C57BL; Molecular immunology; Molecular Sequence Data; Peptides - chemistry; Peptides - immunology; Peptides - metabolism; Temperature; Antigen presentation; Vertebrata; Specificity; Mammalia; Peptides; Mouse; Biological transport; Rodentia; Molecular size; Endoplasmic reticulum; Mechanism; Carrier protein
• ISSN: 0022-1007; 1540-9538
• DOI: 10.1084/jem.179.2.533

The transporter associated with antigen processing (TAP) delivers peptides to the lumen of the endoplasmic reticulum in an adenosine triphosphate (ATP) dependent fashion for presentation by major histocompatibility complex class I molecules. We show that the mouse TAP translocator (H-2b haplotype) selects peptides based on a minimal size of nine residues, and on the presence of a hydrophobic COOH-terminal amino acid. The preponderance of COOH-terminal hydrophobic amino acids in peptides capable of binding to mouse class I molecules thus fits remarkably well with the specificity of the TAP translocator. In addition to transport in the lumenal direction, efflux of peptide in the cytosolic direction is observed in an ATP- and temperature-dependent manner. By maintaining a low peptide concentration at the site of class I assembly, this efflux mechanism may ensure that class I molecules are loaded preferentially with high affinity peptides.