CD63 associates with transmembrane 4 superfamily members, CD9 and CD81, and with beta 1 integrins in human melanoma

CD63 belongs to the Transmembrane 4 superfamily (TM4SF) of membrane proteins whose functions are largely unknown. Previous results have suggested that CD63 may play an important role in the regulation of melanoma progression. To explore the role of CD63 in melanoma we have examined its association with other molecules by immunoprecipitation of CD63 from detergent induced lysates of melanoma cells. These results are the first to demonstrate an association between CD63 and two other TM4SF members, CD9 and CD81 in 2 human melanoma cell lines. We were also able to identify an association between CD9 and CD63 with beta 1 integrins in melanoma. The results suggest that CD63 is capable of forming multicomponent complexes with TM4SF members and beta 1 integrins on the surface of melanoma. These findings provide further insights into the function of CD63. (C) 1996 Academic Press, Inc.