Human Natural Resistance-associated Macrophage Protein 2: Gene Cloning and Protein Identification

The Lsh/Ity/Bcg locus in the mouse genome regulates macrophage activation for antimicrobial activity against intracellular pathogens, and mouse Nramp1 (natural resistance-associated macrophage protein) gene was isolated as its candidate. The human NRAMP1 gene was subsequently isolated and its gene product was identified in macrophage/monocyte cells. Recently, a second Nramp gene, Nramp2, was found in mouse and human genomes. In the present study, we report the cloning and characterization of the human NRAMP2 gene, which is approximately 42 kb in length, containing 16 exons. The transcription start site was determined by 5'-RACE method, and the promoter was located between -246 bp to 145 bp in a region relative to the transcription start site, able to drive the luciferase reporter gene in HeLa cells. We also raised a polyclonal antibody against the glutathione S-transferase fusion protein containing the NH2-terminal 86 amino acids of human NRAMP2. The protein product of the human NRAMP2 gene is apparently present in human cultured cell lines as a 64 kDa protein recognized by this antibody, which is consistent with the molecular mass deduced from the human NRAMP2 cDNA.