Ubiquitination of mammalian Pex5p, the peroxisomal import receptor
Carvalho, Andreia F Pinto, Manuel P Grou, Cláudia P Alencastre, Inês S Fransen, Marc Sá-Miranda, Clara Azevedo, Jorge E # ×
Journal of Biological Chemistry vol:282 issue:43 pages:31267-31272
Protein translocation across the peroxisomal membrane requires the concerted action of numerous peroxins. One central component of this machinery is Pex5p, the cycling receptor for matrix proteins. Pex5p recognizes newly synthesized proteins in the cytosol and promotes their translocation across the peroxisomal membrane. After this translocation step, Pex5p is recycled back into the cytosol to start a new protein transport cycle. Here, we show that mammalian Pex5p is ubiquitinated at the peroxisomal membrane. Two different types of ubiquitination were detected one of which is thiol-sensitive, involves cysteine 11 of Pex5p and is necessary for the export of the receptor back into the cytosol. These findings together with mechanistic data recently described for yeast Pex5p provide strong evidence for the existence of Pex4p- and Pex22p-like proteins in mammals.