Sequence analyses and phylogenetic characterization of the ZIP family of metal ion transport proteins.
Several novel but similar heavy metal ion transporters, Zrt1, Zrt2, Zip1-4 and Irt1, have recently been characterized. Zrt1, Zrt2 and Zip1-4 are probably zinc transporters in Saccharomyces cerevisiae and Arabidopsis thaliana whereas Irt1 appears to play a role in iron uptake in A. thaliana. The family of proteins including these functionally characterized transporters has been designated the Zrt- and Irt-related protein (ZIP) family. In this report, ZIP family proteins in the current databases were identified and multiply aligned, and a phylogenetic tree for the family was constructed. A family specific signature sequence was derived, and the available sequences were analyzed for residues of potential functional significance. A fully conserved intramembranous histidyl residue, present within a putative amphipathic, alpha-helical, transmembrane spanning segment, was identified which may serve as a part of an intrachannel heavy metal ion binding site. The occurrence of a proposed extramembranal metal binding motif (H X H X H) was examined in order to evaluate its potential functional significance for various members of the family. The computational analyses reported in this topical review should serve as a guide to future researchers interested in the structure-function relationships of ZIP family proteins.
Department of Biology, University of California at San Diego, La Jolla, CA 92093-0116, USA.
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Eng
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Guerinot
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Saier
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins; D002352:Carrier Proteins / Q000235:genetics*; D027682:Cation Transport Proteins; D005656:Fungal Proteins / Q000235:genetics; D005800:Genes, Fungal; D017343:Genes, Plant; D017136:Ion Transport; D008565:Membrane Proteins / Q000235:genetics*; D008670:Metals / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017421:Sequence Analysis
D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D027682:Cation Transport Proteins; D005656:Fungal Proteins; C099651:IRT1 protein, Arabidopsis; D008565:Membrane Proteins; D008670:Metals; D010940:Plant Proteins; D029701:Saccharomyces cerevisiae Proteins; C098750:ZRT1 protein, S cerevisiae; C101759:ZRT2 protein, S cerevisiae