NRAMP protein

Kehres, D. G., Zaharik, M. L., Finlay, B. B. and Maguire, M. E. (2000). The NRAMP proteins of Salmonella typhimurium and Escherichia coli are selective manganese transporters involved in the response to reactive oxygen, Mol. Microbiol., 36, 1085-1100. 

A number of genes involved in metal transport in plants have been identified. Many of these belong to previously described transporter families such as the P-type APTases (Axelsen et al. 1998) and the Nramp proteins (natural resistance-associated macrophage protein) (Cellier et al. 

Nramp Natural resistance associated macrophage proteins ... 

Chen, H., G.C. Waldbieser, C.D. Rice, B. Elibol and L.A. Hanson. Isolation and characterization of a channel catfish natural resistance associated macrophage protein (Nramp) gene. Dev. Comp. Immunol. 26 517-531, 2002. 

Saeij, J.P., G.F. Wiegertjes and R.J.M. Stet. Identification and characterization of a fish natural resistance-associated macrophage protein (Nramp) cDNA. Immunogenetics 50 60-66, 1999. 

Rodrigues V, Chia Wand Geos P (1995) Nramp defines a family of membrane proteins. Proc Natl Acad Sci USA 92 10089-10093. 

In addition, recent developments in our understanding of iron uptake and transport provide strong evidence that these systems may also facilitate uptake and transport of lead. Recent smdies on the intestinal iron transporter, Nramp, suggest that this protein may also be responsible for uptake of lead from the intestines into the bloodstream (469). 

Allele frequencies in natural resistance associated macrophage protein (NRAMP) gene may play a role in susceptibility of African American versus Caucasian populations to sarcoidosis (Maliarik et al. 1996). In a case control study of 157 African American patients with sarcoidosis and 111 African American control subjects, Maliarik et al. (2000) found - in contrast to those in tuberculosis patients - the less common genotypes of NRAMP gene more often in control subjects than in case patients. In particular, one polymorphism, a (CA)n repeat in the intermediate 5 region of the gene, was found to have a protective effect (P = 0.014). 

In humans, iron is transported across the gut by a series of poorly defined processes. Fe(III), ferric ion, is absorbed via a J03 integrin and mobilferrin, whereas ferrous ion enter the cells via Nramp. Once inside the body, Fe(III) is transported through the serum by transferrin, a protein of molecular weight 63,000 Da. Fe(III) transferrin is recognized by a receptor protein on the cell surface. Via a process known as cell-mediated endocytosis, the Fe(III) transferrin/receptor complex induces the external cell membrane to pucker and eventually form a clatharin-coated vesicle in the cytoplasm. After removal of the clatharin, the vesicle (known as an endosome) becomes... 

A number of candidate genes have been examined by association. The natural resistance-associated macrophage protein gene (NRAMP) has been associated with susceptibility to tuberculosis. Because of the histopathological similarities with tuberculosis, the association with sarcoidosis was studied (120). A (CA)(n) repeat in the immediate 5 region of the gene was overrepresented in 157 African American patients compared with ethnically matched controls, although the implicated polymorphism differed from both of the two SNPs associated with TB susceptibility. 

Protein families involved in vacuolar sequestration may be the NRAMP s, CDF s, and CAX s (reviewed by Hall and Williams [102]) as well as CPx-type ATPases. Until now, already several transporters for vacuolar sequestration of zinc (and possibly cadmium) and nickel have been investigated and could be partially characterized [103-107]. Several CDF transporters for vacuolar sequestration of Zn (and possibly Cd and Co) have been characterized, all are homologous, almost identical in sequence. These are MTPl, ZAT, and ZTP (e.g., [88,89,103,108]). The strongly elevated expression of the CPx-type metal ATPase HMA3 was shown to play a decisive role in Cd accumulation not only in T. caerulescens [109], but also in rice [110,111], reconfirming also the importance of the sequestration into vacuoles for the hyperaccumulation phenotype. The natural over-expression of NRAMPs was identified both in rice and in T. caerulescens to play an important role in Cd tolerance and possibly Cd accumulation [112-114]. When vacuolar... 

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