NILR-1, a novel immunoglobulin-like receptor expressed by neutrophilic granulocytes, is encoded by a leukocyte receptor gene complex on rat chromosome 1

Several receptors expressed by subsets of leukocytes and with sequence homo logy to the killer cell inhibitory receptors have recently been identified both in man and mouse. Here we describe a rat cDNA that encodes a novel rec eptor of this group, designated neutrophil immunoglobulin-like receptor-1 ( NILR-1). The predicted 58.7-kDa mature NILR-1 protein is a type I integral membrane protein, with three C2-type immunoglobulin superfamily domains, a transmembrane region devoid of charged amino acids, and a cytoplasmic tail containing four immunoreceptor tyrosine-based inhibition motif-like regions . NILR-1 shows greatest sequence homology to the mouse paired immunoglobuli n-like receptor-B and members of the human leukocyte immunoglobulin-like re ceptor/immunoglobulin-like transcript group of receptors. As shown by North ern blot analysis, NILR-1 was transcribed by neutrophilic granulocytes. Alt hough weaker transcription was found with a macrophage cell line, no signal was detected with peritoneal macrophage or spleen RNA. Linkage analysis lo calized Nilr1 to chromosome 1, closely linked to a locus encoding a rat NKp 46 orthologue. The two loci define a rat leukocyte receptor gene complex, i n a region syntenic to human chromosome 19q13.4 and the proximal part of mo use chromosome 7, that harbors the human and mouse leukocyte receptor gene complexes.