Three distinct, but closely related classes of receptors that bind the Fc portion of IgG have been identified (Fcgamma RI, II and III). The FcgammaRI family consists of three closely related genes termed A, B, and C. This gene encodes the low affinity FcgammaRIB receptor that may play an important role in humoral immune response. Alternatively spliced transcript variants encoding different isoforms have been described for this gene. [provided by RefSeq, Oct 2011].