FcRH1, also known as IRTA5 (Immunoglobulin superfamily Receptor Translocation Associated 5), is a type I transmembrane protein having three extracellular Ig-like domains and cytoplasmic ITAM-like motifs. The FcRH subfamily shares sequence homology with the classical receptors for Ig, and the corresponding genes are localized to human chromosome Iq21-23, a hotspot for translocation events involved in B-cell malignancy. FcRH1 is expressed primarily in B cells.