May play an important role in the regulation of lymphoma cell growth. Interacts with a 16-kDa Leu-13 protein to form a complex possibly involved in signal transduction. May act as the viral receptor for HCV. Defects in CD81 are the cause of immunodeficiency common variable type 6 (CVID6); also called antibody deficiency due to CD81 defect. CVID6 is a primary immunodeficiency characterized by antibody deficiency, hypogammaglobulinemia, recurrent bacterial infections and an inability to mount an antibody response to antigen. The defect results from a failure of B-cell differentiation and impaired secretion of immunoglobulins; the numbers of circulating B-cells is usually in the normal range, but can be low. Belongs to the tetraspanin (TM4SF) family. Note: This description may include information from UniProtKB.
Protein type: Membrane protein, integral; Membrane protein, multi-pass
Cellular Component: apical plasma membrane; basolateral plasma membrane; focal adhesion; immunological synapse; integral component of membrane; integral component of plasma membrane; membrane; plasma membrane; vesicle
Molecular Function: protein binding; viral receptor activity
Biological Process: activation of MAPK activity; cell surface receptor signaling pathway; positive regulation of 1-phosphatidylinositol 4-kinase activity; positive regulation of B cell proliferation; positive regulation of cell growth; positive regulation of cell proliferation; positive regulation of peptidyl-tyrosine phosphorylation; positive regulation of transcription from RNA polymerase II promoter; protein localization; receptor internalization; regulation of cell proliferation; regulation of protein stability