The isolation and characterization of the murine T cell antigen receptor ζ chain gene

The T cell antigen receptor (TCR) is a multisubunit complex which has a dual function of antigen recognition and signal transduction. One of its invariant subunits, the ζ chain, has been shown to have a significant role in the expression and function of the TCR on the cell surface. The mouse and human ζ cDNAs share significant homologies to each other but are distinct from all of the previously characterized TCR components. We now report the isolation and structural analysis of the complete murine ζ gene. This gene spans at least 31 kilobases and divides into eight exons. The first exon, which is located at least 20 kilobases upstream from the second exon, codes for the 5'-untranslated region and most of the signal peptide. The second exon codes for the remainder of the signal peptide, the extracellular domain, the transmembrane domain, and the first three amino acids of the intracytoplasmic domain. Exons 3-7 encode the majority of the intracytoplasmic domain. The eight exon encodes the carboxyl-terminal 21 amino acids and the 3'-untranslated region. Four groups of mRNA initiation sites have been identified at approximately 140 base pairs upstream to the AUG codon. No TATA-like box has been detected. The gene is localized to the distal part of chromosome 1 in a linkage group highly conserved between man and mouse.