Paired receptors consist of highly related activating and inhibitory receptors and are widely involved in the regulation of the immune system. Receptor for CD99 and PIANP. Interacts with CD99. 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. PTPN6 seems to bind predominantly to the first ITIM motif (By similarity). Phosphorylated on tyrosine residues.