biostudies-literatureFischer SEuropean Research Council135-155https://www.ebi.ac.uk/biostudies/studies/S-EPMC9929924biostudies-literatureUnknown404(2-3)Peroxisomes are organelles with vital functions in metabolism and their dysfunction is associated with human diseases. To fulfill their multiple roles, peroxisomes import nuclear-encoded matrix proteins, most carrying a peroxisomal targeting signal (PTS) 1. The receptor Pex5p recruits PTS1-proteins for import into peroxisomes; whether and how this process is posttranslationally regulated is unknown. Here, we identify 22 phosphorylation sites of Pex5p. Yeast cells expressing phospho-mimicking Pex5p-S507/523D (Pex5p^2D) show decreased import of GFP with a PTS1. We show that the binding affinity between a PTS1-protein and Pex5p^2D is reduced. An <i>in vivo</i> analysis of the effect of the phospho-mimicking mutant on PTS1-proteins revealed that import of most, but not all,Biological chemistryPhosphorylation of the receptor protein Pex5p modulates import of proteins into peroxisomes.PMC9929924864068Yifrach EFischer SWilmanns MOeljeklaus SMaier RSchuldiner MDrepper FErdmann RPlatta HWGabay-Maskit SObarska-Kosinska ABurgi JZalckvar ERudowitz MMastalski TWarscheid BfalsePhosphorylation of the receptor protein Pex5p modulates import of proteins into peroxisomes.Peroxisomes are organelles with vital functions in metabolism and their dysfunction is associated with human diseases. To fulfill their multiple roles, peroxisomes import nuclear-encoded matrix proteins, most carrying a peroxisomal targeting signal (PTS) 1. The receptor Pex5p recruits PTS1-proteins for import into peroxisomes; whether and how this process is posttranslationally regulated is unknown. Here, we identify 22 phosphorylation sites of Pex5p. Yeast cells expressing phospho-mimicking Pex5p-S507/523D (Pex5p^2D) show decreased import of GFP with a PTS1. We show that the binding affinity between a PTS1-protein and Pex5p^2D is reduced. An <i>in vivo</i> analysis of the effect of the phospho-mimicking mutant on PTS1-proteins revealed that import of most, but not all,2023-01-01T00:00:00Z2023 Feb2026-05-28T11:30:00.142Z2025-02-19T03:26:35.523ZS-EPMC99299243612234710.1515/hsz-2022-0168