CD16, Recombinant, Human (Fc gamma RIII alpha, NK cells)

Fcy RIIIa is a low/intermediate affinity receptor for polyvalent immune-complexed IgG. It is involved in phagocytosis, secretion of enzymes and inflammatory mediators, antibody-dependent cytotoxicity and clearance of immune complexes.1, 2 In humans, it is a 50-70kD type I transmembrane activating receptor expressed by NK cells, T cells, monocytes, and macrophages.1 Fcy RIIIb is highly related, sharing 97% amino acid (aa) identity within the extracellular domain (ECD), but is a GPI-linked receptor expressed on human neutrophils and eosinophils.1, 2 The ECD of Fcy RIIIa shares 63%, 61%, 65%, 59% and 58% aa identity with mouse Fcy RIV, rat Fcy RIIIa, feline CD16, bovine CD16 and porcine Fcy RIIIb paralogs, respectively. The Fcy RIIIa cDNA encodes 254 aa including a 16 aa signal sequence, 191 aa ECD with two C2-type Ig-like domains and five potential N-glycosylation sites, a 22 aa transmembrane (TM) sequence and a 25 aa cytoplasmic domain. In humans, a single nucleotide polymorphism (T230A) creates high binding (176V) and low binding (176F) forms that may influence susceptibility to autoimmune diseases or response to therapeutic IgG antibodies.3, 4 Fcy RIIIa surface expression requires interaction of an accessory chain, either the common y-chain or CD3c.5, 6 Glycosylation patterns, electrophoretic mobility and binding affinity appear to differ between NK cell and monocyte Fcy RIIIa.7 The ECD of both Fcy RIIIa and b can be proteolytically cleaved and retain binding activity in soluble form.8-11 In monocytes and macrophages, activation and phagocytosis can trigger Fcy RIIIa release.11 Soluble Fcy RIII can be detected in normal plasma and is increased in rheumatoid arthritis and in coronary artery diseases.9, 10\n\nA DNA sequence encoding the extracellular domain of human Fcy RIIIa (Gly 17-Gln 208; Accession # AAH17865) was fused with a six-histidine tag at the C-terminus. The chimeric protein was expressed in a mouse myeloma cell line, NS0.\n\nCalculated molecular mass of approximately 22.6kD. As a result of glycosylation, recombinant human Fcy RIIIa migrates as an approximately 40-50kD protein in SDS-PAGE under reducing conditions.\n\nActivity: \nMeasured by its ability to bind human IgG with an estimated KD < 50nM.\n\nStorage and Stability:\nLyophilized powder may be stored at -20 degrees C. Stable for 12 months at -20 degrees C. Reconstitute with PBS. Aliquot and store at -20 degrees C. Reconstituted product is stable for 3 months at -20 degrees C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.

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SPECIFICATIONS

Catalog Number

C2267-31V

Size

50ug

Form

Supplied as a lyophilized powder in PBS. Reconstitute with PBS to (same/more than) 100ug/ml.

Purity

(same/more than) 90%, as determined by SDS-PAGE under reducing conditions and visualized by silver stain. Endotoxin: (same/less than) 1EU/1ug of the protein as determined by the LAL Method.

References

1. Nimmerjahn, F. and Ravetch, J.V., Immunity 24: 19 (2006). 2. Ravetch, J.V. and Perussia, B., J. Exp. Med. 170: 481 (1989). 3. Wu, J., et al., J. Clin. Invest. 100: 1059 (1997). 4. Dall