Crystal structure of the V alpha domain of a T cell antigen receptor.
The crystal structure of the V alpha domain of a T cell antigen receptor (TCR) was determined at a resolution of 2.2 angstroms. This structure represents an immunoglobulin topology set different from those previously described. A switch in a polypeptide strand from one beta sheet to the other enables a pair of V alpha homodimers to pack together to form a tetramer, such that the homodimers are parallel to each other and all hypervariable loops face in one direction. On the basis of the observed mode of V alpha association, a model of an (alpha beta)2 TCR tetramer can be positioned relative to the major histocompatibility complex class II (alpha beta)2 tetramer with the third hypervariable loop of V alpha over the amino-terminal portion of the antigenic peptide and the corresponding loop of V beta over its carboxyl-terminal residues. TCR dimerization that is mediated by the alpha chain may contribute to the coupling of antigen recognition to signal transduction during T cell activation.
Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville, MD 20850, USA.
B A
BA
Fields
B
B
Ober
E L
EL
Malchiodi
M I
MI
Lebedeva
B C
BC
Braden
X
X
Ysern
J K
JK
Kim
X
X
Shao
E S
ES
Ward
R A
RA
Mariuzza
D000818:Animals; D018360:Crystallography, X-Ray; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D011487:Protein Conformation; D017510:Protein Folding; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000737:chemistry* / Q000276:immunology
D016693:Receptors, Antigen, T-Cell, alpha-beta