The protein encoded by this gene is a member of the transmembrane 4 superfamily, also known as the tetraspanin family. Most of these members are cell-surface proteins that are characterized by the presence of four hydrophobic domains. The proteins mediate signal transduction events that play a role in the regulation of cell development, activation, growth and motility. The encoded protein is a cell surface glycoprotein that is known to complex with integrins. It may function as a blood platelet activation marker. Deficiency of this protein is associated with Hermansky-Pudlak syndrome. Also this gene has been associated with tumor progression. Alternative splicing results in multiple transcript variants encoding different protein isoforms. [provided by RefSeq, Apr 2012],function:This antigen is associated with early stages of melanoma tumor progression. May play a role in growth regulation.,miscellaneous:Lack of expression of CD63 in platelets has been observed in a patient with Hermansky-Pudlak syndrome (HPS). Hermansky-Pudlak syndrome (HPS) is a genetically heterogeneous, rare, autosomal recessive disorder characterized by oculocutaneous albinism, bleeding due to platelet storage pool deficiency, and lysosomal storage defects. This syndrome results from defects of diverse cytoplasmic organelles including melanosomes, platelet dense granules and lysosomes. Ceroid storage in the lungs is associated with pulmonary fibrosis, a common cause of premature death in individuals with HPS.,similarity:Belongs to the tetraspanin (TM4SF) family.,subcellular location:Also found in Weibel-Palade bodies of endothelial cells. Located in platelet dense granules.,tissue specificity:Dysplastic nevi, radial growth phase primary melanomas, hematopoietic cells, tissue macrophages.,
