Peroxisomal Remnant Structures in Hansenula polymorpha pex5 Cells Can Develop into Normal Peroxisomes upon Induction of the

We have analyzed the properties of peroxisomal rem-nants in Hansenula polymorpha pex5 cells. In such cells PTS1 matrix protein import is fully impaired. In H. poly-morpha pex5 cells, grown on ethanol/ammonium sulfate, conditions that repressed the PTS2 protein amine oxi-dase (AMO), peroxisomal structures were below the limit of detection. In methanol/ammonium sulfate-grown cells, normal peroxisomes are absent, but a few small membranous structures were observed that ap-parently represented peroxisomal ghosts since they con-tained Pex14p. These structures were the target of a Pex10p.myc fusion protein that was produced in pex5 cells under the control of the homologous alcohol oxi-dase promoter (strain pex5::PAOX.PEX10.MYC). Glycerol/ methanol/ammonium sulfate-grown cells of this trans