title: Hypothesis: a glycoprotein-degradation complex formed by protein-protein interaction involves cytoplasmic peptide:N-glycanase.
abstract: A cytoplasmic peptide:N-glycanase has been implicated in the proteasomal degradation of newly synthesized misfolded glycoproteins that are exported from the endoplasmic reticulum to the cytosol. Recently, the gene encoding this enzyme (Png1p) was identified in yeast and shown to bind to the 26S proteasome through its interaction with a component of the DNA repair system, Rad23p. Moreover, a mouse homologue of Png1p (mPng1p), which has an extended N-terminal domain, was found to bind not only to the Rad23 protein, but also to various proteins related to the ubiquitin/proteasome pathway. An extended N-terminus of mPng1p, which is not found in yeast, contains a potential site of protein-protein interaction called the PUB/PUG domain. The PUB/PUG domain is predicted to be helix-rich and is found in various proteins that may be involved in the ubiquitin/proteasome-related pathway. This review will discuss the consequence of the deglycosylation reaction by peptide:N-glycanase in cellular processes. In addition, the potential importance of the PUB/PUG domain for the formation of a putative "glycoprotein-degradation complex" will be discussed.
authors.affiliation: Undergraduate Program for Bioinformatics and Systems Biology, Graduate School of Science, University of Tokyo and PRESTO, Japan Science and Technology Corporation (JST), Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Suzuki
authors.forename: William J
authors.initials: WJ
authors.lastname: Lennarz
mesh_terms: D000581:Amidohydrolases / Q000378:metabolism*; D000818:Animals; D003593:Cytoplasm / Q000201:enzymology*; D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D006868:Hydrolysis; D051379:Mice; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D011485:Protein Binding; D017510:Protein Folding
chemical_list: D006023:Glycoproteins; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase