Glycobiology and Extracellular Matrices
Letting go of O-glycans
The generation of free N-glycans, or unconjugated oligosaccharides derived from N-linked glycoproteins, is well understood, but whether a similar fate awaits O-linked glycoprotein carbohydrates was unknown. Hirayama et al. now reveal, by using only mannose as an energy source, the generation of free O-glycans in Saccharomyces cerevisiae, in the lumen of a secretory compartment, possibly the vacuole. These findings uncover the presence of a possible regulated degradation pathway for O-mannosylated glycoproteins.Sweet rescue or surrender of the failing heart?
Natriuretic peptides (NPs) are hormones involved in maintaining heart health that undergo proteolytic cleavage to become activated. Previous work has shown that O-GalNAc glycans affect their processing and activation. Here, Goetze, Schjoldager, and colleagues now provide comprehensive characterization of O-glycosylation of NPs, revealing that all members of the NP family can be modified by O-GalNAc glycans. Intriguingly, the study discovers glycans in the receptor-binding region of the A-type natriuretic peptide (ANP), demonstrating that they affect both stability and activity of ANP.
