title: Sorting pathway and molecular targeting signals for the Arabidopsis peroxin 3.
abstract: Peroxin 3 (Pex3p) has been identified and characterized as a peroxisomal membrane protein in yeasts and mammals. We identified two putative homologs in Arabidopsis (AtPex3p, forms 1 and 2), both with an identical cluster of positively charged amino acid residues (RKHRRK) immediately preceding one of the two predicted transmembrane domains (TMD1). In transiently transformed Arabidopsis and tobacco BY-2 suspension-cultured cells, epitope-tagged AtPex3p (form 2) sorted post-translationally from the cytosol directly to peroxisomes, the first sorting pathway described for any peroxin in plants. TMD1 and RKHRRK were necessary for targeting form 2 to peroxisomes and sufficient for directing chloramphenicol acetyltransferase to peroxisomes in both cell types. The N and C termini of AtPex3p (form 2) extend into the peroxisomal matrix, different from mammal and yeast Pex3 proteins. Thus, two authentic peroxisomal membrane-bound Pex3p homologs possessing a membrane peroxisomal targeting signal, the first one defined for a plant peroxin and for any Pex3p homolog, exist in plant cells.
authors.affiliation: School of Life Sciences, Cellular and Molecular Biosciences, Arizona State University, Tempe, AZ 85287-4501, USA.
authors.forename: Joanne E
authors.initials: JE
authors.lastname: Hunt
authors.forename: Richard N
authors.initials: RN
authors.lastname: Trelease
mesh_terms: D018528:ATP-Binding Cassette Transporters; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D000939:Epitopes / Q000737:chemistry; D020224:Expressed Sequence Tags; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D008969:Molecular Sequence Data; D000074401:Peroxins; D020675:Peroxisomes / Q000378:metabolism; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014026:Nicotiana / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D029681:Arabidopsis Proteins; D000939:Epitopes; D008565:Membrane Proteins; C070895:PEX3 protein, S cerevisiae; D000074401:Peroxins; C482059:Pex3 protein, Arabidopsis; D011993:Recombinant Fusion Proteins; C406793:SPF1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins