Cluster of differentiation (CD63) belongs to the tetraspanin family, with four transmembrane domains. It is localised in late endosomes and lysosomes. The gene is located on human chromosome 12q13.2. CD63 is a membrane bound glycoprotein.
Cluster of differentiation (CD63) acts as a platelet activation marker. It plays an important role in regulating cell proliferation, adhesion, motility and differentiation. CD63 acts as a prognostic marker for lung adenocarcinoma. Deficiency of CD63 is associated with Hermansky?Pudlak syndrome (HPS).