The mouse Thy-1.2 glycoprotein gene: complete sequence and identification of an unusual promoter

Recombinant bacteriophage and cosmid clones containing the gene for the mouse Thy-1.2 glycoprotein were isolated and characterized. The complete sequence of the gene was determined, including a previously unidentified exon located 2.1 kb upstream of the portion of the gene encoding the Thy-1.2 glycoprotein. The transcriptional initiation site was located by S1 nuclease protection mapping in both T lymphocytes and neural cells and was found to be located immediately upstream of this exon. S1 nuclease protection mapping was also used to define the 3' end of the Thy-1.2 transcription unit, and no evidence for alternate mRNA processing was found. Thus, the mouse Thy-1.2 gene is 5447 base pairs in length, including promoter sequences, rather than 2094 as previously described. The mouse and rat Thy-1 genes are highly homologous in both introns and exons. However, the mouse Thy-1 cDNA and rat Thy-1 cDNA differ significantly in sequence in the 5' untranslated region. This suggests that the transcriptional initiation site of the mouse and rat genes may be located at different positions within the genomic sequence and may be related to the differing tissue distribution of Thy-1 in the two species.