Eng B H, Guerinot M L, Eide D, Saier M H
Department of Biology, University of California at San Diego, La Jolla, CA 92093-0116, USA.
J Membr Biol. 1998 Nov 1;166(1):1-7. doi: 10.1007/s002329900442.
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.
最近已经鉴定出几种新型但相似的重金属离子转运蛋白，即Zrt1、Zrt2、Zip1 - 4和Irt1。Zrt1、Zrt2和Zip1 - 4可能是酿酒酵母和拟南芥中的锌转运蛋白，而Irt1似乎在拟南芥的铁吸收中发挥作用。包括这些功能已鉴定的转运蛋白在内的蛋白质家族被命名为Zrt和Irt相关蛋白（ZIP）家族。在本报告中，对当前数据库中的ZIP家族蛋白进行了鉴定和多重比对，并构建了该家族的系统发育树。推导了一个家族特异性的特征序列，并对现有序列进行了潜在功能重要性残基的分析。在一个假定的两亲性α螺旋跨膜片段中鉴定出一个完全保守的膜内组氨酸残基，它可能作为通道内重金属离子结合位点的一部分。研究了一个提议的膜外金属结合基序（H X H X H）的出现情况，以评估其对该家族各个成员的潜在功能重要性。本专题综述中报道的计算分析应为对ZIP家族蛋白结构 - 功能关系感兴趣的未来研究人员提供指导。
