STRUCTURE AND EVOLUTION OF A MEMBER OF A NEW SUBFAMILY OF GTP-BINDINGPROTEINS MAPPING TO THE HUMAN MHC CLASS-I REGION

A gene coding for a putative GTP-binding protein MMR1, has been locali zed on band C of the murine Chr 17 within or close to the MHC (Denizot et al. 1992). Its human homolog, HSR1, localized to the human MHC cla ss I region, is described in this paper. Its sequence, compared with M MR1, shows that the conceptual proteins encoded by these genes are hig hly homologous and have thus been subjected to high constraints during evolution. Furthermore. a detailed databank search with HSR1 leads to the characterization of a new subfamily of GTP-binding proteins, of w hich HSR1 and MMR1 are the only eukaryotic members. The precise locali zation of HSR1 within the human MHC class I region is also presented.