The targeting and assembly of peroxisomal proteins: some old rules do not apply

Several proteins have been identified that catalyze the import of proteins into peroxisomes. Some recognize specific peroxisomal targeting sequences, but most probably work further downstream the import pathway. Recent evidence suggests that peroxisomal targeting and assembly do not follow the same rules as those for targeting and import into other organelles, such as the mitochondria and the endoplasmic reticulum, i.e. the import of unfolded proteins and subsequent folding within the organelle. Specifically, proteins may be translocated into the peroxisomal matrix in a folded or oligomerized state.