CD8+ T lymphocytes recognize antigens as short, MHC class I-associated peptides derived by processing of cytoplasmic proteins. The transporter associated with antigen processing translocates peptides from the cytosol into the ER lumen, where they bind to the nascent class I molecules. To date, the precise location of the class I-TAP interaction site remains unclear. We provide evidence that this site is contained within the heavy chain α3 domain. Substitution of a 15 amino acid portion of the H-2Db α3 domain (aa 219-233) with the analogous MHC class II (H-2IAd) β2 domain region (aa 133-147) results in loss of surface expression which can be partially restored upon incubation at 26°C in the presence of excess peptide and β2-microglobulin. Mutant H-2Db (Db219-233) associates poorly with the TAP complex, and cannot present endogenously-derived antigenic peptides requiring TAP-dependent translocation to the ER. However, this presentation defect can be overcome through use of an ER targeting sequence which bypasses TAP-dependent peptide translocation. Thus, the α3 domain serves as an important site of interaction (directly or indirectly) with the TAP complex and is necessary for TAP-dependent peptide loading and class I surface expression.
Physical and Functional Association of the Major Histocompatibility Complex Class I Heavy Chain α3 Domain with the Transporter Associated with Antigen Processing
Address correspondence to Stanislav Vukmanovic, Division of Immunology, Department of Pathology, NYU Medical Center, 550 First Ave., New York 10016. Phone: 212-263-6040; Fax: 212-263-8179; E-mail: [email protected]
1Abbreviations used in this paper: β2m, β2-microglobulin; ER, endoplasmic reticulum; ES, E3/19K leader/signal sequence; NEPHGE, nonequilibrium pH-gradient gel electrophoresis; NP, nucleoprotein; RP10, RPMI 1640/10% FCS; TAP, transporter associated with antigen processing; VV, vaccinia virus; wt, wild type.
Kimary Kulig, Dipankar Nandi, Igor Bacik, John J. Monaco, Stanislav Vukmanovic; Physical and Functional Association of the Major Histocompatibility Complex Class I Heavy Chain α3 Domain with the Transporter Associated with Antigen Processing . J Exp Med 16 March 1998; 187 (6): 865–874. doi: https://doi.org/10.1084/jem.187.6.865
Download citation file:
Sign in
Client Account
Sign in via your Institution
Sign in via your InstitutionEmail alerts
Advertisement