Hypothetical model of peroxisome formation and degradation in yeast. De novo formation of peroxisomes from the endoplasmic reticulum takes place in yeast cells which are devoid of pre-existing peroxisomes (1). In wild-type yeast cells, the predominant mode of peroxisome proliferation occurs via fission of the pre-existing organelles which involves Pex11p dependent elongation and dynamin-related protein (DRP) dependent scission of the peroxisomal membrane. When peroxisomes are targeted for macropexophagy they are engulfed by autophagosomes which ultimately fuse with the vacuolar membrane to deliver the organelle for degradation (2). Peroxisomes can also be targeted for micropexophagy in which the protrusion of the vacuolar membrane engulfs the organelle and they are subsequently degraded (3). MIPA: micropexophagy-specific membrane apparatus.