Pex3p can substitute for Pex3Bp in peroxisome inheritance. (A) pex3BΔ and pex3Δ cells expressing genomically integrated Pot1p-GFP were transformed with empty plasmid pUB4 or pUB4 containing PEX3B or PEX3 for overexpression in oleic acid–containing medium. Cells were grown in YPD supplemented with hygromycin B and then transferred and incubated for 6 h in oleic acid–containing YPBO supplemented with hygromycin B. Fluorescent images of cells were captured by confocal microscopy and deconvolved. Bar, 5 µm. (B) Ultrastructure of pex3BΔ cells overexpressing PEX3B or PEX3. Cells were cultured as in A and then fixed and processed for EM. Arrowheads indicate peroxisomes. Bar, 1 µm. (C) Overexpression of PEX3 can rescue the pex3BΔ phenotype. pex3BΔ cells containing peroxisomes labeled with Pot1p-GFP and the plasmid pUB4 expressing PEX3 under the control of the oleic acid–inducible POT1 promoter were grown and imaged as in Fig. 6 D (see Materials and methods). Representative frames from Video 5 show the specific movements of peroxisomes and their inheritance from mother cell to bud. At 0 min, one large peroxisome cluster is initially located near the mother-bud neck. By 28 min, the peroxisome cluster is split in two by cytokinesis. As new buds emerge, these peroxisome clusters are transferred to the new buds. Several single peroxisomes can be seen at the bud tip by 1 h 36 min. As the buds continue to grow, the peroxisome clusters also move to the bud tips. Bar, 5 µm.