| 背景 | This is recombinant human CD32b (FcgammaRIIb) protein expressed in HEK293 cells, supplied as an in-vivo-grade, ultra-low-endotoxin (<0.5 EU/mg) preparation for research use only. HEK293 expression supports mammalian-type folding and glycosylation, giving a soluble ectodomain suited to biophysical and binding studies. The product is validated for surface plasmon resonance (SPR), biolayer interferometry (BLI), and ELISA, making it well suited to measuring IgG-Fc affinity, ranking antibody variants, and characterising Fc-engineering or effector-function programmes. As a soluble protein rather than a functional antibody, it is used chiefly as an in-vitro reagent, standard, or competitor; the ultra-low endotoxin grade also allows use in endotoxin-sensitive cell assays and in vivo systems where a soluble receptor decoy or spike-in is required. Bulk milligram-to-gram quantities and lot-to-lot consistency support assay development, screening cascades, and reagent standardisation. All content here is guidance for ichorbio to review before publishing.
CD32b (FcgammaRIIb, gene FCGR2B; UniProt P31994) is the only inhibitory Fc gamma receptor, a low-affinity receptor for the Fc region of IgG. Unlike the activating Fc gamma receptors, its cytoplasmic tail carries an immunoreceptor tyrosine-based inhibitory motif (ITIM) that, on co-clustering with activating receptors, recruits the phosphatase SHIP-1 to raise the threshold for immune-cell activation. On B cells, co-ligation of CD32b with the B-cell receptor dampens B-cell activation and antibody production, providing a key peripheral tolerance checkpoint. It is also expressed on myeloid cells, dendritic cells, and basophils, where it tempers activation and controls immune-complex responses. CD32b sets the activating-to-inhibitory receptor balance that governs the potency of many therapeutic antibodies and is itself a target and Fc-engineering consideration in antibody drug development. |
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