PIR-A/B (Paired Ig-like Receptor-A, PIR-A)

Paired Ig-like Receptor-B (PIR-B) is a 125kD type I transmembrane glycoprotein with six Ig-like domains in its extracellular domain (ECD) and four ITIM-like sequences in its cytoplasmic domain. The ECD of PIR-B is highly homologous to the ECDs of multiple mouse PIR-A receptors (92‑99% amino acid sequence homology), which have short cytoplasmic tails lacking ITIM motifs. PIR-A receptors have a charged residue in their transmembrane domain that facilitates interaction with ITAM-containing adaptor molecules. Whereas PIR-A receptors deliver activation signals, PIR-B can inhibit receptor-mediated activation...