Inhibitory receptor which may contribute to the down-regulation of cytolytic activity in natural killer (NK) cells, and to the down-regulation of mast cell degranulation. Negatively regulates the Toll-like receptor (TLR) signaling mediated by MYD88 but not TRIF through activation of PTPN6. Upon tyrosine-phosphorylation, interacts with PTN6/SHP-1 and PTPN11/SHP-2 and INPP5D. Phosphorylated on tyrosine. N-glycosylated. Belongs to the CD300 family.