Direct evidence of cytosolic PNGase activity in Arabidopsis thaliana: in vitro assay system for plant cPNGase activity.

Cytosolic peptide: N-glycanase (cPNGase), which occurs ubiquitously in eukaryotic cells, is involved in the de-N-glycosylation of misfolded glycoproteins in the protein quality control system. In this study, we aimed to provide direct evidence of plant cPNGase activity against a denatured glycoprotein using a crude extract prepared from a mutant line of Arabidopsis thaliana lacking two acidic PNGase genes.