1KTD

CRYSTAL STRUCTURE OF CLASS II MHC MOLECULE IEK BOUND TO PIGEON CYTOCHROME C PEPTIDE

Summary for 1KTD

• Entry DOI: 10.2210/pdb1ktd/pdb
• Related: 1KT2
• Descriptor: H-2 class II histocompatibility antigen, E-D alpha chain, Fusion protein consisting of cytochrome C peptide, glycine rich linker, and MHC E-beta-k, 2-acetamido-2-deoxy-beta-D-glucopyranose, ... (5 entities in total)
• Functional Keywords: protein-peptide complex, t cell receptor, antigen presentation, cytochrome, immune system
• Biological source: Mus musculus (Mouse); More
• Total number of polymer chains: 4
• Total formula weight: 92090.58

Authors

Fremont, D.H.,Dai, S.,Chiang, H.,Crawford, F.,Marrack, P.,Kappler, J. (deposition date: 2002-01-15, release date: 2002-05-01, Last modification date: 2024-10-30)

Primary citation

Fremont, D.H.,Dai, S.,Chiang, H.,Crawford, F.,Marrack, P.,Kappler, J.
Structural basis of cytochrome c presentation by IE(k).
J.Exp.Med., 195:1043-1052, 2002

PubMed Abstract: The COOH-terminal peptides of pigeon and moth cytochrome c, bound to mouse IE(k), are two of the most thoroughly studied T cell antigens. We have solved the crystal structures of the moth peptide and a weak agonist-antagonist variant of the pigeon peptide bound to IE(k). The moth peptide and all other peptides whose structures have been solved bound to IE(k), have a lysine filling the p9 pocket of IE(k). However, the pigeon peptide has an alanine at p9 shifting the lysine to p10. Rather than kinking to place the lysine in the anchor pocket, the pigeon peptide takes the extended course through the binding groove, which is characteristic of all other peptides bound to major histocompatibility complex (MHC) class II. Thus, unlike MHC class I, in which peptides often kink to place optimally anchoring side chains, MHC class II imposes an extended peptide conformation even at the cost of a highly conserved anchor residue. The substitution of Ser for Thr at p8 in the variant pigeon peptide induces no detectable surface change other than the loss of the side chain methyl group, despite the dramatic change in recognition by T cells. Finally, these structures can be used to interpret the many published mutational studies of these ligands and the T cell receptors that recognize them.

PubMed: 11956295
DOI: 10.1084/jem.20011971

Experimental method

X-RAY DIFFRACTION (2.4 Å)