PEX14P IS A MEMBER OF THE PROTEIN LINKAGE MAP OF PEX5P

To identify members of the translocation machinery for peroxisomal pro teins, we made use of the two-hybrid system to establish a protein lin kage map centered around Pex5p from Saccharomyces cerevisiae, the rece ptor for the C-terminal peroxisomal targeting signal (PTS1), Among the five interaction partners identified, Pex14p was found to be induced under conditions allowing peroxisome proliferation. Deletion of the co rresponding gene resulted in the inability of yeast cells to grow on o leate as well as the absence of peroxisomal structures, The PEX14 gene product of similar to 38 kDa was biochemically and ultrastructurally demonstrated to be a peroxisomal membrane protein, despite the lack of a membrane-spanning domain. This protein was shown to interact with i tself, with Pex13p and with both PTS receptors, Pex5p and Pex7p, indic ating a central function for the import of peroxisomal matrix proteins , either as a docking protein or as a releasing factor at the organell ar membrane.