CD81 Antigen (CD81) Human Recombinant Protein

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. This encoded protein is a cell surface glycoprotein that is known to complex with integrins. This protein appears to promote muscle cell fusion and support myotube maintenance. Also it may be involved in signal transduction. This gene is localized in the tumor-suppressor gene region and thus it is a candidate gene for malignancies. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2014]

CD81: 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.

Protein type: Membrane protein, multi-pass; Membrane protein, integral

Chromosomal Location of Human Ortholog: 11p15.5

Cellular Component: apical plasma membrane; focal adhesion; immunological synapse; integral to plasma membrane; membrane; plasma membrane; vesicle

Molecular Function: protein binding

Biological Process: activation of MAPK activity; cell proliferation; cell surface receptor linked signal transduction; entry of virus into host cell; positive regulation of 1-phosphatidylinositol 4-kinase activity; positive regulation of B cell proliferation; 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 growth; regulation of immune response; regulation of protein stability; response to wounding; virion attachment, binding of host cell surface receptor

Disease: Immunodeficiency, Common Variable, 6