Cloning and comparative analisys of the human pre-T-cell receptor a-chain gene.

In immature T cells the T-cell receptor (TCR) beta-chain gene is rearranged 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 pT alpha cDNA as a probe, we have isolated the human pT alpha cDNA. The complete nucleotide sequence predicts a mature protein of 282 aa consisting of an extracellular immunoglobulin-like domain, a connecting peptide, a transmembrane region, and a long cytoplasmic tail. Amino acid sequence comparison of human pT alpha with the mouse pT alpha molecule reveals high sequence homology in the extracellular as well as the transmembrane region, In contrast, the cytoplasmic region differs in amino acid composition and in length from the murine homologue. The human 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.