3QIW: Crystal Structure Of The 226 Tcr In Complex With Mcc-P5eI-Ek

T cells specific for the cytochrome c Ag are widely used to investigate many aspects of TCR specificity and interactions with peptide-MHC, but structural information has long been elusive. In this study, we present structures for the well-studied 2B4 TCR, as well as a naturally occurring variant of the 5c.c7 TCR, 226, which is cross-reactive with more than half of possible substitutions at all three TCR-sensitive residues on the peptide Ag. These structures alone and in complex with peptide-MHC ligands allow us to reassess many prior mutagenesis results. In addition, the structure of 226 bound to one peptide variant, p5E, shows major changes in the CDR3 contacts compared with wild-type, yet the TCR V-region contacts with MHC are conserved. These and other data illustrate the ability of TCRs to accommodate large variations in CDR3 structure and peptide contacts within the constraints of highly conserved TCR-MHC interactions.
PDB ID: 3QIWDownload
MMDB ID: 90190
PDB Deposition Date: 2011/1/27
Updated in MMDB: 2011/08
Experimental Method:
x-ray diffraction
Resolution: 3.3  Å
Source Organism:
Mus musculus
Similar Structures:
Biological Unit for 3QIW: pentameric; determined by author and by software (PISA)
Molecular Components in 3QIW
Label Count Molecule
Proteins (5 molecules)
H-2 Class II Histocompatibility Antigen, E-K Alpha Chain(Gene symbol: H2-Ea-ps)
Molecule annotation
MHC Class II H2-ia-beta Chain
Molecule annotation
TCR 226 Alpha Chain
Molecule annotation
TCR 226 Beta Chain
Molecule annotation
Mcc-p5e Peptide
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB