PEX19P, A FARNESYLATED PROTEIN ESSENTIAL FOR PEROXISOME BIOGENESIS

We report the identification and molecular characterization of Pex19p, an oleic acid-inducible, farnesylated protein of 39.7 kDa that is ess ential for peroxisome biogenesis in Saccharomyces cerevisiae. Cells la cking Pex19p are characterized by the absence of morphologically detec table peroxisomes and mislocalization of peroxisomal matrix proteins t o the cytosol. The human HK33 gene product was identified as the putat ive human ortholog of Pex19p. Evidence is provided that farnesylation of Pex19p takes place at the cysteine of the C-terminal CKQQ amino aci d sequence. Farnesylation of Pex19p was shown to be essential for the proper function of the protein in peroxisome biogenesis. Pex19p was sh own to interact with Pex3p in vivo, and this interaction required farn esylation of Pex19p.