Current evidence favors a cycling receptor model for the import of peroxisomal matrix proteins. The yeast Pex14 protein together with Pex13p and Pex17p forms the docking subcomplex at the peroxisomal membrane and interacts in this cycle with both soluble import receptors, Pex5p and Pex7p. In a first step of a structure-function analysis of Saccharomyces cerevisiae Pex14p, we mapped its binding sites with both receptors. Using the yeast two-hybrid system and pull-down assays we show that Pex5p interacts with two separate regions of ScPex14p, amino acid residues 1-59 and 235-308. The latter binding site at the C-terminus of ScPex14p overlaps with the binding site of Pex7p at amino acid residues 235-325. The functional assessment of these two binding sites of ScPex14p with the PTS receptors indicates that they have distinct roles. Deletion of the N-terminal 58 amino acids caused a partial defect of matrix protein import in delta pex14 cells expressing the Pex14(59-341)p fragment, however, it did not lead to a pex phenotype. In contrast, truncation of the C-terminal 106 amino acids of ScPex14p completely blocked this process. On the basis of these, and other published data, we propose that the C-terminus of Pex14p contains the actual docking site and discuss the possibility that the N-terminus could be involved in a Pex5p-Pex14p association inside the peroxisomal membrane.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|