Core glycan in the yeast multicopper ferroxidase, Fet3p: A case study of N-linked glycosylation, protein maturation, and stability

摘要: Glycosylation is essential to the maintenance of protein quality in vesicular trafficking pathway eukaryotic cells. Using yeast multicopper oxidase, Fet3p, hypothesis tested that core glycosylation suppresses Fet3p nascent chain aggregation during synthesis into endoplasmic reticulum (ER). has 11 crystallographically mapped N-linked glycan units. Assembly four these units specifically required for localization plasma membrane (PM). Fet3 lacking any one found an intracellular high-molecular mass species resolvable by blue native gel electrophoresis. Individually, remaining moieties are not ER exit; however, serial deletion N → A substitution correlates with desglycan failure exit ER. Desglycan proteins localize PM wild type function indicating missing carbohydrate structure and biologic activity. This includes interaction iron permease, Ftr1p, high-affinity uptake The sequons within relatively nonpolar regions located surface recesses strongly conserved among fungal proteins. sites more exposed, less environments, their conservation weak or absent. data indicate little effect on enzyme's molecular activity but critical its cellular maximizing protein's from assembly a functional complex.