CD46 (MEMBRANE COFACTOR PROTEIN OF COMPLEMENT, MEASLES-VIRUS RECEPTOR) - STRUCTURAL AND FUNCTIONAL DIVERGENCE AMONG SPECIES (REVIEW)

Human CD46 was identified as a complement regulator and was later show n to be a measles virus receptor. The ubiquitous distribution profile of CD46 accounted for systemic measles infection and general protectio n of host tissue/organs from autologous complement. A similar ubiquito us distribution was observed fdr swine and simian CD46 homologues base d upon subsequent cDNA cloning and Northern analysis, reinforcing the roles of CD46. In contrast, recent cDNA cloning and distribution analy ses of murine and guinea-pig CD46 revealed the predominant expression of these rodent CD46 homologues in the testis, especially in mature te sticular germ cells. These results do not support the established func tions of human CD46 but support the hypothesis that CD46 on sperm serv es as a fertilization-related adhesion molecule toward eggs. Here, we review the structure, function and distribution of human CD46 and disc uss the possible differences between human CD46 and its homologues rec ently cloned from a variety of non-human primates and other animals.