Physiological and molecular functions of the cytosolic peptide:N-glycanase

Peptide:N-glycanase (PNGase) is a deglycosylating enzyme that acts on N-glycoproteins. A growing evidence exists to indicate that the cytosolic form of PNGase, which is ubiquitously distributed throughout eukaryotes, is not only implicated in the efficient degradation of misfolded glycoproteins destined for the proteasomal degradation but also in the generation of free oligosaccharides as the initial step in the non-lysosomal catabolism of N-glycans. This article summarizes the current state of our knowledge of the physiological and molecular functions of the cytosolic PNGase in a model organism, Saccharomyces cerevisiae, and also discusses the functional/structural diversities of this molecule within eukaryotes.