The unfolding story of T cell receptor ‘ y

Antigen-specific, major histocompatability complexrestricted recognition by classical T cells is mediated by a T cell receptor (TCR) consisting of a disulfidelinked aj3 heterodimer. During the search for the genes encoding the a and /3 proteins, a third immunoglobulinlikegene, termed y, was uncovered. Like the 7CR a and /3genes, the TCR -ygene consistsof variable and constant segments that rearrange during T cell development in the thymus. Although the physiological role of TCR y remains an enigma, much has been learned with the recent identification of the protein products of thisgene family in both mice and humans. The y chain is associated with a partner chain, termed b. The -yb heterodimer is associated with an invariant T3 complex, very similar to that associated with the af3 heterodimer, and appears predominantly, if not exclusively, on cells with a CD4, CD8 phenotype both in the thymus and in the periphery.TCR -yb is the first T3-associated receptor to appear during thymocyte development and defines a separate T cell lineage distinct from crf3-bearingcells.Although TCR cr/3bearing cellsand TCR -yb-bearing cells follow parallel developmental pathways, the diversity of expressed ‘yb receptors is extremely limited relative to that of ct/3 receptors. PARDOLL, D. M.; KRUISBEEK, A. M.; FOWLKES, B. J.;COLIGAN, J.E.;SCHWARTZ, R. H. The unfolding story of T cell receptor -y. FASEB j 1: