| 背景 | This product is a recombinant human CD32a (FcgammaRIIa) protein, corresponding to the R131 (Arg131) allotype implied by the "167R" designation, expressed in human embryonic kidney (HEK) 293 cells. HEK293 expression provides human-type glycosylation and correct disulfide folding of the two extracellular Ig-like domains, supporting native-like ligand recognition. The protein is manufactured to an ultra-low endotoxin specification (<0.5 EU/mg), which minimizes confounding TLR4-driven activation in cell-based and functional readouts and makes it suitable for sensitive in-vitro and ex-vivo work as well as any downstream in-vivo application the investigator validates. It is supplied research-use-only (RUO) and is available in bulk (mg to gram) quantities for assay development and screening campaigns. The validated applications are surface plasmon resonance (SPR), bio-layer interferometry (BLI), and ELISA, reflecting its primary use as a purified soluble ectodomain for characterizing antibody Fc engagement, Fc-engineering, and Fc-receptor binding kinetics. As a defined recombinant antigen it is well suited to affinity ranking, epitope/allotype comparison, and quality-control assays. Lot-specific purity, sequence boundaries, tag configuration, and endotoxin values should be confirmed on the certificate of analysis.
CD32a (FcgammaRIIa, gene FCGR2A; UniProt P12318) is a low-to-moderate affinity activating receptor for the Fc region of IgG, expressed on monocytes, macrophages, neutrophils, dendritic cells, and platelets. It is a single-pass transmembrane glycoprotein with two extracellular Ig-like domains that engage the lower hinge/CH2 region of IgG, preferentially binding immune complexes and aggregated IgG over monomeric IgG. Unlike most Fc receptors, CD32a signals through an ITAM motif contained within its own cytoplasmic tail rather than through a separate gamma-chain, triggering phagocytosis, antibody-dependent cellular cytotoxicity, respiratory burst, degranulation, and cytokine release. A well-known functional polymorphism at position 131 (His131 versus Arg131) alters affinity for human IgG subclasses, particularly IgG2, and influences responses to therapeutic and pathogen-directed antibodies. On platelets, CD32a contributes to IgG-mediated activation relevant to immune thrombocytopenia and heparin-induced thrombocytopenia. |
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