PMID: 21572394

 

    Legend: Sugar

Title : Nogo-B receptor is necessary for cellular dolichol biosynthesis and protein N-glycosylation

Abstract :

1. Dolichol monophosphate (Dol-P) functions as an obligate glycosyl carrier lipid in protein glycosylation reactions
2. Dol-P is synthesized by the successive condensation of isopentenyl diphosphate ( IPP ), with farnesyl diphosphate catalysed by a cis-isoprenyltransferase ( cis-IPTase ) activity
3. Despite the recognition of cis-IPTase activity 40 years ago and the molecular cloning of the human cDNA encoding the mammalian enzyme , the molecular machinery responsible for regulating this activity remains incompletely understood
4. Here, we identify Nogo-B receptor ( NgBR ) as an essential component of the Dol-P biosynthetic machinery
5. Loss of NgBR results in a robust deficit in cis-IPTase activity and Dol-P production, leading to diminished levels of dolichol-linked oligosaccharides and a broad reduction in protein N-glycosylation
6. NgBR interacts with the previously identified cis-IPTase hCIT , enhances hCIT protein stability, and promotes Dol-P production
7. Identification of NgBR as a component of the cis-IPTase machinery yields insights into the regulation of dolichol biosynthesis