title: Characterization of the preprotein and amino acid transporter gene family in Arabidopsis.
abstract: Seventeen loci encode proteins of the preprotein and amino acid transporter family in Arabidopsis (Arabidopsis thaliana). Some of these genes have arisen from recent duplications and are not in annotated duplicated regions of the Arabidopsis genome. In comparison to a number of other eukaryotic organisms, this family of proteins has greatly expanded in plants, with 24 loci in rice (Oryza sativa). Most of the Arabidopsis and rice genes are orthologous, indicating expansion of this family before monocot and dicot divergence. In vitro protein uptake assays, in vivo green fluorescent protein tagging, and immunological analyses of selected proteins determined either mitochondrial or plastidic localization for 10 and six proteins, respectively. The protein encoded by At5g24650 is targeted to both mitochondria and chloroplasts and, to our knowledge, is the first membrane protein reported to be targeted to mitochondria and chloroplasts. Three genes encoded translocase of the inner mitochondrial membrane (TIM)17-like proteins, three TIM23-like proteins, and three outer envelope protein16-like proteins in Arabidopsis. The identity of Arabidopsis TIM22-like proteins is most likely a protein encoded by At3g10110/At1g18320, based on phylogenetic analysis, subcellular localization, and complementation of a yeast (Saccharomyces cerevisiae) mutant and coexpression analysis. The lack of a preprotein and amino acid transporter domain in some proteins, localization in mitochondria, plastids, or both, variation in gene structure, and the differences in expression profiles indicate that the function of this family has diverged in plants beyond roles in protein translocation.
authors.affiliation: Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley, Western Australia 6009, Australia.
authors.forename: Monika W
authors.initials: MW
authors.lastname: Murcha
authors.forename: Dina
authors.initials: D
authors.lastname: Elhafez
authors.forename: Ryan
authors.initials: R
authors.lastname: Lister
authors.forename: Julian
authors.initials: J
authors.lastname: Tonti-Filippini
authors.forename: Manuela
authors.initials: M
authors.lastname: Baumgartner
authors.forename: Katrin
authors.initials: K
authors.lastname: Philippar
authors.forename: Chris
authors.initials: C
authors.lastname: Carrie
authors.forename: Dejana
authors.initials: D
authors.lastname: Mokranjac
authors.forename: Jürgen
authors.initials: J
authors.lastname: Soll
authors.forename: James
authors.initials: J
authors.lastname: Whelan
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000032:analysis / Q000145:classification / Q000235:genetics*; D002352:Carrier Proteins / Q000032:analysis / Q000145:classification / Q000235:genetics*; D002736:Chloroplasts / Q000378:metabolism; D005816:Genetic Complementation Test; D018745:Genome, Plant; D026901:Membrane Transport Proteins / Q000235:genetics; D008928:Mitochondria / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D012333:RNA, Messenger / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D016415:Sequence Alignment
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; C102549:TIM22 protein, S cerevisiae