We have analyzed the presence of peroxisomal remnants (‘ghosts’) in three peroxisome-deficient (per) mutants of the yeast Hansenula polymorpha, namely Δper4, Δper5 and Δper10. Under peroxisome-inducing growth conditions peroxisomal membrane proteins (PMPs) were normally synthesized in cells of these mutants. In addition, these cells contained clusters of small membranous vesicles, which were absent in cells grown under peroxisome-repressing growth conditions. These structures displayed typical peroxisomal properties in that they proliferated upon overproduction of Per8p, the H. polymorpha peroxisome proliferation factor. Moreover, in Δper4 and Δper5 these vesicles were susceptible to glucose-induced proteolytic degradation.
