Leukocyte Associated Immunoglobulin Like Receptor 1 (LAIR1)

LAIR1 is a type I membrane protein with a leader sequence, an extracellular domain, a transmembrane domain, and a cytoplasmic region. LAIR-1 is a 32 kDa transmembrane glycoprotein with a single immunoglobulin-like domain and a cytoplasmic tail containing two immune receptor tyrosine-based inhibitory motifs. LAIR-1 recruits SHP-1 and SHP-2 phosphatases upon activation, and cross-linking of the LAIR-1 antigen on natural killer (NK) cells results in strong inhibition of NK cell-mediated cytotoxicity. Although it is structurally related to human killer cell inhibitory receptors, LAIR-1 does not appear to recognize human leukocyte antigen (HLA) class I molecules and thus represents a novel HLA class I-independent mechanism of NK cell regulation.