The human homologue of the mouse t-complex gene, TCP1, is located on chromosome 6 but is not near the HLA region.

Southern blot analysis indicates that there are four sequences in the human genome related to the mouse t-complex gene Tcp-1. All four genes were cloned and partial sequencing showed that one of them was a functional gene, and the other three were pseudogenes. The human sequences were all approximately 90% related to each other and 82-89% related to the mouse Tcp-1a sequence. Human TCP1 cDNA clones from both fibrosarcoma and B cell lines confirmed that there was a single expressed gene. mRNA transcripts of different sizes were accounted for by two different polyadenylation signals. The human TCP1 gene shared some amino acid substitutions with the mouse t-complex allele (Tcp-1a) which were not found in Tcp-1b. The functional human TCP1 gene was mapped, using a panel of somatic cell hybrids, as well as in situ analysis, to the long arm of chromosome 6 at 6q23-qter and thus is not closely linked to the HLA complex on the short arm. For this reason and others it is unlikely that there is a human equivalent of the mouse t-complex.