1AKJ

COMPLEX OF THE HUMAN MHC CLASS I GLYCOPROTEIN HLA-A2 AND THE T CELL CORECEPTOR CD8

Summary for 1AKJ

• Entry DOI: 10.2210/pdb1akj/pdb
• Descriptor: MHC CLASS I HISTOCOMPATIBILITY ANTIGEN (HLA-A*0201) (ALPHA CHAIN), BETA 2-MICROGLOBULIN, HIV REVERSE TRANSCRIPTASE EPITOPE, ... (5 entities in total)
• Functional Keywords: t-cell, glycoprotein, complex, immunology, complex (mhc i-peptide-cd8), complex (mhc i-peptide-cd8) complex, complex (mhc i/peptide/cd8)
• Biological source: Homo sapiens (human); More
• Cellular location: Membrane; Single-pass type I membrane protein: P01892; Secreted: P61769; Isoform 1: Cell membrane; Single-pass type I membrane protein. Isoform 2: Secreted: P01732
• Total number of polymer chains: 5
• Total formula weight: 71645.22

Authors

Tormo, J.,Stuart, D.I.,Jones, E.Y. (deposition date: 1997-05-21, release date: 1997-09-17, Last modification date: 2024-10-23)

Primary citation

Gao, G.F.,Tormo, J.,Gerth, U.C.,Wyer, J.R.,McMichael, A.J.,Stuart, D.I.,Bell, J.I.,Jones, E.Y.,Jakobsen, B.K.
Crystal structure of the complex between human CD8alpha(alpha) and HLA-A2.
Nature, 387:630-634, 1997

PubMed Abstract: The dimeric cell-surface glycoprotein CD8 is crucial to the positive selection of cytotoxic T cells in the thymus. The homodimer CD8alpha(alpha) or the heterodimer alpha beta stabilizes the interaction of the T-cell antigen receptor (TCR) with major histocompatibility complex (MHC) class I/peptide by binding to the class I molecule. Here we report the crystal structure at 2.7 A resolution of a complex between CD8alpha(alpha) and the human MHC molecule HLA-A2, which is associated with peptide. CD8alpha(alpha) binds one HLA-A2/peptide molecule, interfacing with the alpha2 and alpha3 domains of HLA-A2 and also contacting beta2-microglobulin. A flexible loop of the alpha3 domain (residues 223-229) is clamped between the complementarity-determining region (CDR)-like loops of the two CD8 subunits in the classic manner of an antibody-antigen interaction, precluding the binding of a second MHC molecule. The position of the alpha3 domain is different from that in uncomplexed HLA-A2, being most similar to that in the TCR/Tax/HLA-A2 complex, but no conformational change extends to the MHC/peptide surface presented for TCR recognition. Although these shifts in alpha3 may provide a synergistic modulation of affinity, the binding of CD8 to MHC is clearly consistent with an avidity-based contribution from CD8 to TCR-peptide-MHC interactions.

PubMed: 9177355
DOI: 10.1038/42523

Experimental method

X-RAY DIFFRACTION (2.65 Å)