T-cell receptor (TCR)

Antigen receptors on the surfaces of T cells are
heterodimers of covalently bound polypeptide
chains, one " and one % chain. The basic structure
of a cell surface antigen receptor is similar
to that of the secreted immunoglobulins except
that the cell surface receptors contain just one
constant region. The % chain is the slightly
larger chain. The constant regions of the " and %
chains (C) each consist of 140–180 amino acids.
The variable regions (V) consist of 102–109
amino acids and contain three hypervariable regions,
like the immunoglobulin molecules. In
addition to those for " and %, genes for a T-cellreceptor
& and # chain exist. The loci for the
TCR", &, and # chains in man lie together on
chromosome 14; the locus for TCR% lies on
chromosome 13.