Detected in spleen, bone marrow, thymus, ovary and lung. Contains 3 copies of a cytoplasmic motif that is referred to as the immunoreceptor tyrosine-based inhibitor motif (ITIM). This motif is involved in modulation of cellular responses. The phosphorylated ITIM motif can bind the SH2 domain of several SH2-containing phosphatases, including PTPN6/SHP-1, resulting in the dephosphorylation of the downstream protein kinases SYK and BTK.