Fcgr4, also known as Fc Receptor-like 3 (Fcrl3) and CD16-2, is a recently described mouse protein that is closely related to human Fc gamma RIIIA (60% amino acid identity) and may be its true ortholog. Similar to other activating receptors, it possesses a charged residue within its transmembrane domain that is necessary for association with an ITAM bearing accessory protein. CD16-2 mRNA expression was observed in peripheral blood leukocytes, spleen, thymus, colon, and intestine.