FcγRIIB (Fc fragment of IgG receptor IIb), aslo known as Fc gamma RIIB, FCGR2B or CD32B, is a 34 kDa protein that is encoded by the FCGR2B gene located on the chromosome 1q23.3. It has a length of 310 amino acids and produces a low-affinity inhibitory receptor for immunoglobulin G (IgG). In humans, FcγRIIB is composed of two alternatively spliced subunits, FcγRIIb1 and FcγRIIb2. It is a predominant Fc receptor (FcR) on B cells and is a founding member of immunoreceptor tyrosine-based inhibitory motif (ITIM) family of immune inhibitory receptors. A motif within the cytoplasmic tail of FcγRIIb termed ITIM, confers the ability to inhibit cellular activation mediated by immunoreceptor tyrosine-based inhibition motif (ITAM)-bearing receptors. Inhibition only occurs when FcγRIIB is co-clustered with an ITAM-bearing immunoreceptor. CD79b/CD79B (Cluster of differentiation 79B), also referred to CD79b antigen (Immunoglobulin-associated beta), B29, IGB or AGM6, is a B lymphocyte antigen receptor complex-associated protein beta chain with 229 amino acids. It has a molecular weight of 26 kDa and is encoded by human B29 gene mapping at the chromosome 17q23.3. The protein CD79b and CD79a collectively constitute CD79. Among them, CD79b is responsible for the Ig-beta protein recognition of the B-lymphocyte antigen receptor while CD79a recognizes the Ig-alpha. Ig-alpha and Ig-beta protein, non-covalentl associated with B-cell surface Ig, are necessary for the expression and biological function of the B-lymphocyte antigen receptor. CD79 is a potent marker for B-cell lineage and is found in most types of B-cell and in some myelomas.