| 背景 | This is a recombinant human CD16a protein carrying the 176V (high-affinity) polymorphic variant, produced in HEK293 cells so that it retains mammalian folding and glycosylation. As a HEK-expressed extracellular-domain protein it is well suited to biophysical and functional binding studies rather than in-vivo dosing: it is characterised for label-free kinetics by SPR and BLI and for plate-based ELISA. The In Vivo Grade, Ultra-Low Endotoxin designation (<0.5 EU/mg) makes it appropriate for endotoxin-sensitive cell-based assays, ADCC and effector-function work, and reagent formats where contaminating LPS would confound results. Supplied as an RUO reagent in bulk-compatible quantities, it is intended for research applications such as antibody Fc-engineering screens, FcgammaRIIIa affinity ranking of therapeutic candidates, competition assays, and biosensor surface capture. UniProt P08637 corresponds to the human FCGR3A gene product. Investigators should confirm lot-specific concentration, tag configuration, and activity before use, and validate binding in their own assay system.
CD16a (FcgammaRIIIa), encoded by FCGR3A (UniProt P08637), is a low-to-intermediate affinity activating Fc receptor for IgG. It is expressed chiefly on natural killer cells, monocytes/macrophages, and some gammadelta T cells, where it couples IgG-opsonised targets to effector responses. On NK cells, CD16a engagement of clustered IgG Fc triggers antibody-dependent cell-mediated cytotoxicity (ADCC) and cytokine release, a mechanism central to the activity of many therapeutic monoclonal antibodies. A functional polymorphism at position 158 in the mature protein (numbered 176 including signal peptide, hence the 176V designation) determines Fc affinity: the valine (V) variant binds IgG1 and IgG3 more tightly than the phenylalanine (F) variant and is associated with stronger ADCC and, clinically, with improved responses to several antibody therapeutics. Receptor N-glycosylation further modulates IgG affinity. |
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