Alternative routes for synthesis of N-linked glycans by Alg2 mannosyltransferase

What is it about?

N-glycosylation is the most abundant post translational modification in eukaryotic cells. This paper describes our study of the Alg2 glycosyltransferase and its unique bifunctionality during synthesis of lipid-linked oligosaccharide (LLO), the initial step of N-glycosylation. Despite the importance of these essential reactions, Alg2 biochemical properties are controversial and have remain undefined. We demonstrated that addition of the α1,3- and α1,6-mannose can occur independently, leading to a new model in which alternative, independent routes exist for Alg2 catalysis of the trimannosyl core oligosaccharide. This finding is a shift in the current paradigm, in which all steps of LLO synthesis are of a requisite order.

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