Alexa Fluor® 647 Mouse Anti-Human CD9 Antibody (S-2896)

CD9, a 24-kDa cell-surface glycoprotein belonging to the tetraspanin family, is characterized by four transmembrane domains and two extracellular loops; it is widely expressed (e.g., on platelets, B/T cells, macrophages, and oocytes) and organizes tetraspanin-enriched microdomains that integrate membrane and cytoplasmic proteins to regulate adhesion, migration, proliferation, survival, and immune synapse formation. Notably, CD9 is essential for mammalian gamete fusion, as CD9-null eggs cannot fuse with wild-type sperm, and anti-CD9 antibodies block sperm–egg binding and fusion in vitro. Additionally, CD9 is implicated in platelet activation, signal transduction, and is frequently detected in lymphoblastic leukemia/lymphoma and some acute myeloid leukemia cells.