Export of Antigenic Peptides from the Endoplasmic Reticulum Intersects with Retrograde Protein Translocation through the Sec61p Channel

• Published in: Immunity (Cambridge, Mass.) Mass.), 2000-07, Vol.13 (1), p.117-127
• Main Authors: Koopmann, Jens-Oliver, Albring, Jörn, Hüter, Eva, Bulbuc, Nadja, Spee, Pieter, Neefjes, Jacques, Hämmerling, Günter J, Momburg, Frank
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; ADP Ribose Transferases; Animals; Antigens - metabolism; ATP Binding Cassette Transporter, Subfamily B, Member 2; ATP-Binding Cassette Transporters - metabolism; b2-microglobulin; Bacterial Toxins - metabolism; Biological Transport, Active; Endoplasmic Reticulum - metabolism; Exotoxins - metabolism; Membrane Proteins - metabolism; Mice; Peptides - metabolism; Proteins - metabolism; Pseudomonas aeruginosa - metabolism; Pseudomonas aeruginosa Exotoxin A; Rabbits; SEC Translocation Channels; Sec61 protein; TAP protein; Virulence Factors
• ISSN: 1074-7613; 1097-4180
• DOI: 10.1016/S1074-7613(00)00013-3

Antigenic peptides are translocated by the TAP peptide transporter from the cytosol into the endoplasmic reticulum (ER) for loading onto MHC class I molecules. Peptides that fail to bind need to be removed from the ER. Here we provide evidence that peptide export utilizes the Sec61p translocon as demonstrated by blocking this channel with bacterial exotoxin. Peptide export interferes with the retrotranslocation of β2-microglobulin from the ER to the cytosol, suggesting similar pathways for the disposal of proteins and oligopeptides. Peptide export requires ATP supply to the ER lumen but is independent of ATP hydrolysis.