Fc gamma RIIa Recombinant Protein

Background:

Receptors for the Fc region of IgG (Fc gamma R) are members of the Ig superfamily that function in the activation or inhibition of immune responses. Human Fc gamma Rs are divided into three classes designated Fc gamma RI (CD64), Fc gamma RII (CD32), and Fc gamma RIII (CD16), which generate multiple isoforms, are recognized. The activating­ type receptor either has or associates non­covalently with an accessory subunit that has an immunoreceptor tyrosine­based activation motif (ITAM) in its cytoplasmic domain. Fc gamma RI binds IgG with high affinity and functions during early immune responses, whereas Fc gamma RII and RIII are low affinity receptors that recognize IgG as aggregates surrounding multivalent antigens during late immune responses. Three genes for human Fc gamma RII (A, B, and C) and one for mouse (Fc gamma RIIB), encoding type I transmembrane proteins with ITAM motifs (Fc gamma RII A and C) or ITIM motifs (Fc gamma RIIB) in their cytoplasmic domains, have been identified. Human CD32, also known as Low affinity immunoglobulin gamma Fc region receptor II-a (IgG Fc receptor II-a), Fc gamma RII A or FCGR2A Protein, is expressed on cells of both myeloid and lymphoid lineages as well as on cells of non-hematopoietic origin. Associated with an ITAM-bearing adapter subunit, FcR gamma , CD32a (Fc gamma RII A) delivers an activating signal upon ligand binding, and results in the initiation of inflammatory responses including cytolysis, phagocytosis, degranulation, and cytokine production. The responses can be modulated by signals from the co-expressed inhibitory receptors such as Fc gamma RII B, and the strength of the signal is dependent on the ratio of expression of the activating and inhibitory receptors.