Cell surface receptor, which is involved in signal transduction processes. Recruits PTPN11/SHP-2 to the cell membrane and is a putative substrate of PTPN11/SHP-2. Is a major receptor for concanavalin-A (ConA) and is involved in cellular signaling induced by ConA, which probably includes Src family tyrosine-protein kinases. Isoform 3 seems to have a dominant negative role; it blocks tyrosine phosphorylation of MPZL1 induced by ConA. Isoform 1, but not isoform 2 and isoform 3, may be involved in regulation of integrin-mediated cell motility. Interacts with phosphorylated PTPN11/SHP-2. Widely expressed with highest levels in heart, placenta, kidney and pancreas. Isoform 3 is relatively abundant in hematopoietic tissues and fetal liver. Isoform 1 and isoform 3 are expressed in CD14- PB monocytes and pre-B cell progenitors. Isoform 3 appears to be the major isoform in CD34- promyelocytic and promonocytic cells. During differentiation in monocytic cells, the expression level of isoform 3 decreases and that of isoform 1 increases. Isoform 1 is prominent in stromal cells and, to a lesser extent, in umbilical vein endothelial cells and erythroid progenitors. Isoform 2 is expressed in a erythroid progenitor cell line. Contains 2 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. Phosphorylated on tyrosine residues upon stimulation with pervanadate and concanavalin-A (ConA). Phosphorylation at Tyr-241 and Tyr-263 is required for interaction with PTPN11/SHP-2. Dephosphorylated by PTPN11/SHP-2 (in vitro). N-glycosylated. N-glycosylation is required for concanavalin A binding (PubMed:30392906). Belongs to the myelin P0 protein family.