GENOMIC STRUCTURE AND CHROMOSOMAL LOCATION OF THE MOUSE PRE-T-CELL RECEPTOR-ALPHA GENE

The mouse pre-T-cell receptor alpha (pT alpha) chain is a 33000 M(r) g lycoprotein expressed on the surface of immature thymocytes as a disul fide-linked heterodimer with the T-cell receptor beta (TCR beta) chain , and in association with proteins of the CD3 complex. The cDNA for pT alpha isolated previously, encodes a type I transmembrane protein tha t is a member of the immunoglobulin (Ig) superfamily. Here we report t he complete nucleotide sequence, the exon/intron structure, and the ch romosomal location of the pT alpha gene. The gene spans about 8.4 kilo bases (kb) and consists of four exons. Exon 1 encodes the 5' untransla ted region, the leader peptide, and the first three amino acids of the mature protein. This exon is followed by a relatively long intron of 4.9 kb that contains many short interspersed repeats (SINEs) of the B1 and B2 family. The second exon encodes the extracellular Ig-Like doma in and exon 3 with just 45 base pairs the connecting peptide (CP), inc luding the cysteine required for heterodimer formation. A similar exon /intron structure encoding corresponding parts of the mature polypepti de is found both in the Tcra and Tcrd constant region genes. The last exon encodes the transmembrane portion, the cytoplasmic tail, and abou t 540 nucleotides of 3' untranslated sequence, including a B2 repetiti ve element. In situ hybridization maps the pTa gene to the D/E1 region of mouse chromosome 17.