InterPro domain: IPR001046

The natural resistance-associated macrophage protein (NRAMP) family consists of Nramp1, Nramp2, and yeast proteins Smf1 and Smf2. The NRAMP family is a novel family of functionally related proteins defined by a conserved hydrophobic core of ten transmembrane domains [ 1 ]. Nramp1 is an integral membrane protein expressed exclusively in cells of the immune system and is recruited to the membrane of a phagosome upon phagocytosis. Nramp2 is a multiple divalent cation transporter for Fe2+, Mn2+ and Zn2+ amongst others. It is expressed at high levels in the intestine; and is major transferrin-independent iron uptake system in mammals [ 2 ]. The yeast proteins Smf1 and Smf2 may also transport divalent cations [ 3 ].

The natural resistance of mice to infection with intracellular parasites iscontrolled by the Bcg locus, which modulates the cytostatic/cytocidalactivity of phagocytes. Nramp1, the gene responsible, is expressed exclusively inmacrophages and poly-morphonuclear leukocytes, and encodes a polypeptide(natural resistance-associated macrophage protein) with features typical of integralmembrane proteins. Other transporter proteins from a variety of sources also belongto this family.

1. Nramp defines a family of membrane proteins. Proc. Natl. Acad. Sci. U.S.A. 92, 10089-93
2. Macrophage NRAMP1 and its role in resistance to microbial infections. Inflamm. Res. 47, 277-84
3. Metal ion homeostasis and intracellular parasitism. Mol. Microbiol. 28, 403-12