Molecular cloning, characterization, and chromosomal localization of the mouse homologue of CD84, a member of the CD2 family of cell surface molecules

CD84 is a member of the immunoglobulin gene superfamily (IgSF) with two Ig- like domains expressed primarily on B lymphocytes and macrophages. Here we describe the cloning of the mouse homologue of human CD84. Mouse CD84 cDNA clones were isolated from a macrophage library. The nucleotide sequence of mouse CD84 was shown to include an open reading frame encoding a putative 3 29 amino acid protein composed of a 21 amino acid leader peptide, two extra cellular immunoglobulin (Ig)-like domains, a hydrophobic transmembrane regi on, and an 87 amino acid cytoplasmic domain. Mouse CD84 shares 57.3% amino acid sequence identity (88.7%, considering conservative amino acid substitu tions) with the human homologue. Chromosome localization studies mapped the mouse CD84 gene to distal chromosome 1 adjacent to the gene for Ly-9, plac ing it close to the region where other members of the CD2 IgSF (CD48 and 2B 4) have been mapped. Northern blot analysis revealed that the expression of mouse CD84 was predominantly restricted to hematopoietic tissues. Two spec ies of mRNA. of 3.6 kilobases (kb) and 1.5 kb were observed. The finding th at the pattern of expression was restricted to the hematopoietic system and the conserved sequence of the mouse CD84 homologue suggests that the funct ion of the CD84 glycoprotein may be similar in humans and mice.