CD317 Recombinant Protein

BST2 (CD317, Tetherin, HM1.24) is a type II transmembrane glycoprotein functioning as a major mediator of the innate immune defense against the dissemination of enveloped viruses by tethering viron on cell surface. BST2 has a N-terminal cytoplasmic tail for entocytosis and cytoskelatal signaling, a transmembrane domain, an extracellular domain containing putative disulfide bonds and coiled coil region for forming homodimer, and a C-terminal GPI domain for membran anchoring. Both the transmembrane domain and the GPI domain can insert either to the cell membrane or the viral envelope membrane and hold them together to prevent viral release. Virus counteracts BST2 by encoding viral protein as antagonist. These viral proteins interact directly with BST2 to either enhance BST2 endocytosis/lysosomal degradation (such as Vpu) or prevent BST2 secretion pathway by sequestering the protein in endosome. BST2 is overexpressed in gastrointestinal cancers, breast cancer, lung cancer and multiple myeloma. BST2 monoclonal antibody targeting myeloma or lung cancer cells induces celllular cytotoxicity and cell death (ADCC, antibody-dependent cell-mediated cytotoxicity) . Thus BST2 serves as a potential target for tumor immunotherapy.