Dolichyl-diphosphooligosaccharide--protein glycosyltransferase subunit 1

RPN1 (dolichyl-diphosphooligosaccharide–protein glycosyltransferase subunit 1) is a core component of the oligosaccharyl transferase (OST) complex, which catalyzes the transfer of a conserved glycan (Glc₃Man₉GlcNAc₂) from a lipid carrier to asparagine residues on nascent polypeptides, initiating protein N-glycosylation (UniProt: P04843). This modification occurs cotranslationally as the complex associates with the Sec61 translocon channel during endoplasmic reticulum protein translocation. All OST subunits, including RPN1, are required for maximal enzyme activity.

RPN1 functions in the endoplasmic reticulum and is central to the early secretory pathway and protein quality control. N-glycosylation is essential for proper protein folding, trafficking, and immune recognition across diverse cellular proteins. The UniProt record lists no primary disease associations.

RPN1 is upregulated in Alzheimer's disease brain tissue. Analysis of post-mortem AD brain versus age-matched controls using TMT-labeled proteomics across four subcellular fractions identified RPN1 as elevated (mean log₂FC = 0.39, detected in 2 fractions; Chaparral AD proteomics). This upregulation may reflect altered ER protein synthesis and glycoprotein processing in AD neurodegeneration, though further mechanistic investigation is warranted.