CD81 [SEP] found in taxon
E2 glycoproteins heterodimer. The large extracellular loop(LEL) of CD81 binds the hepatitis E2 glycoprotein dimer. HCV-E2 and CD81 binding Kd is 1.8 nM. HCV-E2 engaged CD81 is only 30% internalized after 12hr, suggesting CD81 may be primarily an attachment receptor for HCV.
It also appears to play a role in liver invasion by "Plasmodium" species. CD81 is required for "Plasmodium vivax" sporozoite entry into human hepatocytes and for "Plasmodium yoelii" sporozoite entry into murine hepatocytes.
HIV gag proteins use tetraspanin
interactions with cells of the immune system. Finally, tetraspanin proteins, including CD9, CD37, CD63 and CD81 are one of the most abundant protein families found in microvesicle membranes. Many of these proteins may be involved in the sorting and selection of specific cargos to be loaded into the lumen of the microvesicle or its membrane.
Other than lipids and proteins, microvesicles are enriched with nucleic acids (e.g., messenger RNA (mRNA) and microRNA (miRNA). The identification of RNA molecules in microvesicles supports the hypothesis that