CD81 Protein, Mouse (HEK293, His)

CD81 is a protein that plays a crucial role in various cellular processes. It is involved in the trafficking and compartmentalization of the CD19 receptor on the surface of activated B cells. This facilitates the assembly of CD19-CR2 and B cell receptor complexes, which lowers the threshold dose of antigen required to trigger B cell clonal expansion and immune response. In T cells, CD81 associates with CD4 or CD8 coreceptors and helps define the maturation state of synapses with B cells. It also facilitates the localization of CD3 in immune synapses, which is necessary for T cell activation and costimulation. CD81 can act as both a positive and negative regulator of cell-cell fusion processes. In myoblasts, it associates with CD9 and PTGFRN to inhibit myotube fusion during muscle regeneration. In macrophages, CD81 prevents fusion into multinucleated giant cells and osteoclasts. It also regulates sperm-egg fusion and may be involved in the acrosome reaction. CD81 is involved in protein trafficking within intracellular compartments and regulates intracellular dNTP levels in T cells. Additionally, it plays a role in integrin-dependent migration of macrophages and is specifically required for the infectivity of Plasmodium yoelii in hepatocytes during malaria infection.