1KJM

TAP-A-associated rat MHC class I molecule

Summary for 1KJM

• Entry DOI: 10.2210/pdb1kjm/pdb
• Related: 1ED3 1KJV
• Descriptor: RT1 class I histocompatibility antigen, AA alpha chain, heavy chain, beta-2-Microglobulin, B6 Peptide, ... (5 entities in total)
• Functional Keywords: peptide-mhc complex, heterodimer, extracellular domain, immune system
• Biological source: Rattus norvegicus (Norway rat); More
• Cellular location: Membrane; Single-pass type I membrane protein: P16391; Secreted: P07151
• Total number of polymer chains: 3
• Total formula weight: 46131.48

Authors

Rudolph, M.G.,Stevens, J.,Speir, J.A.,Trowsdale, J.,Butcher, G.W.,Joly, E.,Wilson, I.A. (deposition date: 2001-12-04, release date: 2002-12-18, Last modification date: 2024-11-20)

Primary citation

Rudolph, M.G.,Stevens, J.,Speir, J.A.,Trowsdale, J.,Butcher, G.W.,Joly, E.,Wilson, I.A.
Crystal structures of two rat MHC class Ia (RT1-A) molecules that are associated differentially with peptide transporter alleles TAP-A and TAP-B.
J.Mol.Biol., 324:975-990, 2002

PubMed Abstract: Antigenic peptides are loaded onto class I MHC molecules in the endoplasmic reticulum (ER) by a complex consisting of the MHC class I heavy chain, beta(2)-microglobulin, calreticulin, tapasin, Erp57 (ER60) and the transporter associated with antigen processing (TAP). While most mammalian species transport these peptides into the ER via a single allele of TAP, rats have evolved different TAPs, TAP-A and TAP-B, that are present in different inbred strains. Each TAP delivers a different spectrum of peptides and is associated genetically with distinct subsets of MHC class Ia alleles, but the molecular basis for the conservation (or co-evolution) of the two transporter alleles is unknown. We have determined the crystal structures of a representative of each MHC subset, viz RT1-A(a) and RT1-A1(c), in association with high-affinity nonamer peptides. The structures reveal how the chemical properties of the two different rat MHC F-pockets match those of the corresponding C termini of the peptides, corroborating biochemical data on the rates of peptide-MHC complex assembly. An unusual sequence in RT1-A1(c) leads to a major deviation from the highly conserved beta(3)/alpha(1) loop (residues 40-59) conformation in mouse and human MHC class I structures. This loop change contributes to profound changes in the shape of the A-pocket in the peptide-binding groove and may explain the function of RT1-A1(c) as an inhibitory natural killer cell ligand.

PubMed: 12470953
DOI: 10.1016/S0022-2836(02)01095-1

Experimental method

X-RAY DIFFRACTION (2.35 Å)