Figure 5. De novo formation of peroxisomes requires Pex25p.
A) Mutant cells lacking PEX11, PEX25 and PEX27, expressing PEX3 under the control of the GAL promoter (pex11Δpex25Δpex27Δpex3Δ::GAL-PEX3) and transformed with plasmids expressing Pex11p, Pex25p or Pex27p were grown in the presence of 2% glucose with or without a short period of exposure to 2% galactose 8 h prior to microscopic inspection. Peroxisomes were visualized by fluorescence microscopy (mCherry-px; red channel). Bar: 2 µm. B) Microscopic analysis of yeast cells lacking INP2 and one, two or three members of the PEX11 family and expressing GFP-px under the control of the GAL promoter (green channel). The corresponding DNA sequence was integrated into the INP2 locus. After growth on glucose for 16 h, cells were shifted to medium containing 1% raffinose and 2% galactose for 6 h and thinly seeded on microscope slides covered with agarose containing the same medium. After 10 h, colonies originating from single cells were inspected for the distribution of green fluorescence emitted from GFP-px. Arrows point to elongated peroxisomes. Images in (A) and (B) represent projected Z-stacks. Bar: 5 µm.