Primary structure of human T-cell receptor α-chain

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Abstract
The T-cell receptor has been studied intensely over the past 10 years in an effort to understand the molecular basis for major histocompatibility complex (MHC) restricted antigen recognition1–9. The use of anti-receptor monoclonal antibodies to isolate and characterize the receptor from human and murine T-cell clones10–15 has shown that the protein consists of two disulphide-linked glycopeptides, α and β, distinct from known immunoglobulin light and heavy chains. Like immunoglobulin light and heavy chains, however, both the α- and β-chains are composed of variable and constant regions16–18. Molecular cloning has revealed19–23 that the β-chain is evolutionarily related to immunoglobulins, and is encoded in separate V (variable), D (diversity), J (joining) and C (constant) segments that are rearranged in T cells to produce a functional gene19–21,24–27. We report here cDNA clones encoding the α-chain of the receptor of the human T-cell leukaemia line HPB-MLT. Using these cDNA probes, we find that expression of α-chain mRNA and rearrangement of an α-chain V-gene segment occur only in T cells. The protein sequence predicted by these cDNAs is homologous to T-cell receptor β-chains and to immunoglobulin heavy and light chains, particularly in the V and J segments.