title: Pex13p is an SH3 protein of the peroxisome membrane and a docking factor for the predominantly cytoplasmic PTs1 receptor.
abstract: Import of newly synthesized PTS1 proteins into the peroxisome requires the PTS1 receptor (Pex5p), a predominantly cytoplasmic protein that cycles between the cytoplasm and peroxisome. We have identified Pex13p, a novel integral peroxisomal membrane from both yeast and humans that binds the PTS1 receptor via a cytoplasmically oriented SH3 domain. Although only a small amount of Pex5p is bound to peroxisomes at steady state (< 5%), loss of Pex13p further reduces the amount of peroxisome-associated Pex5p by approximately 40-fold. Furthermore, loss of Pex13p eliminates import of peroxisomal matrix proteins that contain either the type-1 or type-2 peroxisomal targeting signal but does not affect targeting and insertion of integral peroxisomal membrane proteins. We conclude that Pex13p functions as a docking factor for the predominantly cytoplasmic PTS1 receptor.
authors.affiliation: Department of Biological Chemistry, Johns Hopkins University School of Medicine, Kennedy Krieger Institute, Baltimore, Maryland 21205, USA. Stephen.Gould@qmail.bs.jhu.edu
authors.forename: S J
authors.initials: SJ
authors.lastname: Gould
authors.forename: J E
authors.initials: JE
authors.lastname: Kalish
authors.forename: J C
authors.initials: JC
authors.lastname: Morrell
authors.forename: J
authors.initials: J
authors.lastname: Bjorkman
authors.forename: A J
authors.initials: AJ
authors.lastname: Urquhart
authors.forename: D I
authors.initials: DI
authors.lastname: Crane
mesh_terms: D000101:Acetyl-CoA C-Acetyltransferase / Q000378:metabolism; D000595:Amino Acid Sequence; D001692:Biological Transport; D002374:Catalase / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry*; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism; D005347:Fibroblasts; D005796:Genes / Q000235:genetics; D005800:Genes, Fungal / Q000235:genetics; D006801:Humans; D007425:Intracellular Membranes / Q000737:chemistry; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D008830:Microbodies / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D000074437:Peroxisomal Targeting Signal 2 Receptor; D000074435:Peroxisome-Targeting Signal 1 Receptor; D010843:Pichia / Q000235:genetics; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D018909:src Homology Domains
chemical_list: D015815:Cell Adhesion Molecules; D008565:Membrane Proteins; C101884:PEX13 protein, human; D000074437:Peroxisomal Targeting Signal 2 Receptor; D000074435:Peroxisome-Targeting Signal 1 Receptor; D018160:Receptors, Cytoplasmic and Nuclear; D002374:Catalase; D000101:Acetyl-CoA C-Acetyltransferase