title: Import of proteins into peroxisomes: piggybacking to a new home away from home.
abstract: Peroxisomes are capable of importing folded and oligomeric proteins. However, it is a matter of dispute whether oligomer import by peroxisomes is the exception or the rule. Here, I argue for a clear distinction between homo-oligomeric proteins that are essentially peroxisomal, and dually localized hetero-oligomers that access the peroxisome by piggyback import, localizing there in limited number, whereas the majority remain in the cytosol. Homo-oligomeric proteins comprise the majority of all peroxisomal matrix proteins. There is evidence that binding by Pex5 in the cytosol can regulate their oligomerization state before import. The hetero-oligomer group is made up of superoxide dismutase and lactate dehydrogenase. These proteins have evolved mechanisms that render import inefficient and retain the majority of proteins in the cytosol.
authors.affiliation: Department of Child and Adolescent Medicine, University Medical Center, University of Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany sven.thoms@med.uni-goettingen.de.
authors.forename: Sven
authors.initials: S
authors.lastname: Thoms
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D006801:Humans; D008969:Molecular Sequence Data; D000074435:Peroxisome-Targeting Signal 1 Receptor; D020675:Peroxisomes / Q000378:metabolism*; D055503:Protein Multimerization; D021381:Protein Transport; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry / Q000378:metabolism*
chemical_list: C000614264:PEX5 protein, human; D000074435:Peroxisome-Targeting Signal 1 Receptor; D018160:Receptors, Cytoplasmic and Nuclear
keywords: PTS1; Pex5; cellular organelles; peroxisome; piggyback import; protein import