CLONING AND COMPARATIVE-ANALYSIS OF THE HUMAN PRE-T-CELL RECEPTOR ALPHA-CHAIN GENE

In immature T cells the T-cell receptor (TCR) beta-chain gene is rearr anged and expressed before the TCR alpha-chain gene. At this stage TCR beta chain can form disulfide-linked heterodimers with the pre-T-cell receptor alpha chain (pT alpha). Using the recently isolated murine p T alpha cDNA as a probe, we have isolated the human pT alpha cDNA. The complete nucleotide sequence predicts a mature protein of 282 aa cons isting of an extracellular immunoglobulin-like domain, a connecting pe ptide, a transmembrane region, and a long cytoplasmic tail. Amino acid sequence comparison of human pT alpha with the mouse pT alpha molecul e reveals high sequence homology in the extracellular as well as the t ransmembrane region, In contrast, the cytoplasmic region differs in am ino acid composition and in length from the murine homologue. The huma n pT alpha gene is expressed in immature but not mature T cells and is located at the p21.2-p12 region of the short arm of chromosome 6.