Protein N-glycosylation pathway (Dolichol pathway) (LLO pathway)

The protein N-glycosylation pathway, also known as the dolichol-linked oligosaccharide (LLO) biosynthesis pathway, is a fundamental post-translational modification process occurring in the endoplasmic reticulum (ER). It involves the stepwise assembly of a core oligosaccharide on a dolichol-phosphate lipid carrier, which is then transferred en bloc to asparagine residues of nascent polypeptides by the oligosaccharyltransferase (OST) complex. This pathway is critical for proper protein folding, stability, and trafficking, and its dysregulation is linked to various diseases, including cancer, where aberrant glycosylation promotes tumor progression and metastasis. Therapeutic targeting of the pathway, particularly through the inhibition of the rate-limiting enzyme DPAGT1 by compounds like tunicamycin or newer selective inhibitors, aims to induce ER stress and apoptosis in malignant cells. However, the essential nature of N-glycosylation in normal physiology presents significant challenges regarding systemic toxicity and the need for high selectivity. Beyond cancer, the pathway is also a target for antiviral therapies, as many viral envelope proteins require N-glycosylation for proper assembly and host cell entry. Additionally, genetic defects in this pathway lead to a group of rare metabolic disorders known as Congenital Disorders of Glycosylation (CDG). Monitoring the pathway's activity often involves analyzing the glycosylation status of serum proteins like transferrin.

Other names

Dolichol-linked oligosaccharide biosynthesisN-linked glycosylation pathwayLLO biosynthesisDolichol pathway

Inhibition of UDP-GlcNAc:dolichyl-phosphate GlcNAc-1-phosphate transferase (DPAGT1), inhibition of oligosaccharyltransferase (OST), and depletion of dolichol-phosphate precursors.