IDENTIFICATION OF A NOVEL, TISSUE-SPECIFIC CALPAIN HTRA-3, A HUMAN HOMOLOG OF THE CAENORHABDITIS-ELEGANS SEX DETERMINATION GENE

We cloned a novel human gene encoding a tissue specific calpain, terme d htra-3, which is highly homologous to the tra-3 sex determination ge ne of Caenorhabditis elegans. The predicted htra-3 polypeptide had sim ilarity to the calpain large subunits in domain organization throughou t domains I to III, but the sequences of domain IV lacked calcium-bind ing motifs. Northern blot analysis revealed high expression in the col on, small intestine and testis. Radiation hybrid mapping localized the htra-3 gene to chromosome 11q14 (2.53cR apart from WI-3895). Western blot analysis demonstrated that the approximately 73-kDa htra-3 protei n was transiently expressed in COS-7 cells. These observations, togeth er with the genetic information in C. elegans, suggest a unique functi on for htra-3 protein. (C) 1997 Academic Press.