title: The peroxisomal receptor dislocation pathway: to the exportomer and beyond.
abstract: The biogenesis of peroxisomes is an ubiquitin-dependent process. In particular, the import of matrix proteins into the peroxisomal lumen requires the modification of import receptors with ubiquitin. The matrix proteins are synthesized on free polyribosomes in the cytosol and are recognized by import receptors via a peroxisomal targeting sequence (PTS). Subsequent to the transport of the receptor/cargo-complex to the peroxisomal membrane and the release of the cargo into the peroxisomal lumen, the PTS-receptors are exported back to the cytosol for further rounds of matrix protein import. The exportomer represents the molecular machinery required for the retrotranslocation of the PTS-receptors. It comprises enzymes for the ubiquitination as well as for the ATP-dependent extraction of the PTS-receptors from the peroxisomal membrane. Furthermore, recent evidence indicates a mechanistic interconnection of the ATP-dependent removal of the PTS-receptors with the translocation of the matrix protein into the organellar lumen. Interestingly, the components of the peroxisomal exportomer seem also to be involved in cellular tasks that are distinct from the ubiquitination and dislocation of the peroxisomal PTS-receptors. This includes work that indicates a central function of this machinery in the export of peroxisomal matrix proteins in plants, while a subset of exportomer components is involved in the meiocyte formation in some fungi, the peroxisome-chloroplast contact during photorespiration in plants and possibly even the selective degradation of peroxisomes via pexophagy. In this review, we want to discuss the central role of the exportomer during matrix protein import, but also highlight distinct roles of exportomer constituents in additional cellular processes. This article is part of a Special Issue entitled: Peroxisomes: biogenesis, functions and diseases.
authors.affiliation: Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum, Germany. Electronic address: harald.platta@rub.de.
authors.forename: Harald W
authors.initials: HW
authors.lastname: Platta
authors.affiliation: Systembiochemie, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Hagen
authors.affiliation: Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Reidick
authors.affiliation: Systembiochemie, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum, Germany. Electronic address: ralf.erdmann@rub.de.
authors.forename: Ralf
authors.initials: R
authors.lastname: Erdmann
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000502:physiology; D029681:Arabidopsis Proteins / Q000502:physiology; D018797:Cell Cycle Proteins / Q000502:physiology; D003600:Cytosol / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D008565:Membrane Proteins / Q000502:physiology; D026901:Membrane Transport Proteins / Q000502:physiology; D000074401:Peroxins; D000074435:Peroxisome-Targeting Signal 1 Receptor; D020675:Peroxisomes / Q000502:physiology*; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology; D025801:Ubiquitin / Q000378:metabolism; D054875:Ubiquitination; D000074405:Valosin Containing Protein
chemical_list: D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C499509:PEX5 protein, S cerevisiae; D000074401:Peroxins; D000074435:Peroxisome-Targeting Signal 1 Receptor; D029701:Saccharomyces cerevisiae Proteins; C462525:TED3 protein, Arabidopsis; D025801:Ubiquitin; C085380:peroxisomal targeting sequence receptor; D000251:Adenosine Triphosphatases; D000074183:ATPases Associated with Diverse Cellular Activities; C000614177:CDC48 protein, S cerevisiae; C490761:PEROXIN6 protein, Arabidopsis; D000074405:Valosin Containing Protein
keywords: AAA-type ATPases; Peroxin; Peroxisome; Protein import; RING-type ligase; Ubiquitination