Characterization of peroxisomal Pex5p from rat liver. Pex5p in the Pex5p-Pex14p membrane complex is a transmembrane protein.
Pex5p is the receptor for the vast majority of peroxisomal matrix proteins. Here, we show that about 15% of rat liver Pex5p is found in the peroxisomal fraction representing 0.06% of total peroxisomal protein. This population of Pex5p displays all the characteristics of an intrinsic membrane protein. Protease protection assays indicate that this pool of Pex5p has domains exposed on both sides of the peroxisomal membrane. The strong interaction of Pex5p with the membrane of the organelle is not affected by mild protease treatment of intact organelles, conditions that result in the partial degradation of Pex13p. Cytosolic Pex5p is a monomeric protein. In contrast, virtually all peroxisomal Pex5p was found to be part of a stable 250-kDa protein assembly. This complex was isolated and shown to comprise just two subunits, Pex5p and Pex14p.
Gouveia
A M
AM
Instituto de Biologia Molecular e Celular and Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, 4150-180 Porto, Portugal.
Reguenga
C
C
Oliveira
M E
ME
Sa-Miranda
C
C
Azevedo
J E
JE
D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D002458:Cell Fractionation; D003600:Cytosol / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism* / Q000648:ultrastructure; D008099:Liver / Q000378:metabolism* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D008958:Models, Molecular; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D000074435:Peroxisome-Targeting Signal 1 Receptor; D020675:Peroxisomes / Q000378:metabolism* / Q000648:ultrastructure; D017433:Protein Structure, Secondary; D021122:Protein Subunits; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012097:Repressor Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D002352:Carrier Proteins; D008565:Membrane Proteins; C455539:PEX14 protein, human; D010446:Peptide Fragments; D000074435:Peroxisome-Targeting Signal 1 Receptor; C499194:Pex14 protein, rat; D021122:Protein Subunits; D018160:Receptors, Cytoplasmic and Nuclear; D011994:Recombinant Proteins; D012097:Repressor Proteins