Endoglycosidase and Glycoamidase Release of N‐Linked Oligosaccharides

Abstract

Nearly all proteins entering the lumen of the endoplasmic reticulum (ER) become glycosylated en route to a cellular organelle, the plasma membrane, or the extracellular space. Many glycans can be attached to proteins, but the most common are the N-linked oligosaccharides. These chains are added very soon after a protein enters the ER, but they undergo extensive remodeling (processing), especially in the Golgi. Processing changes the sensitivity of the N-glycan to enzymes that cleave entire sugar chains or individual monosaccharides, which also changes the migration of the protein on SDS gels. These changes can be used to indicate when a protein has passed a particular subcellular location. This unit details some of the methods used to track a protein as it traffics from the ER to the Golgi toward its final location.

Molecular cloning, expression, and functional features of IGF1 splice variants in sheep

“…Further, IGF1 Ea contained the N-linked glycosylation site based on the Asn-X-Ser/Thr sequence, whereas Eb lacked this site due to the reading frame shift. This N-linked glycosylation could regulate intracellular IGF1 Ea levels by preventing proteasome-mediated degradation [34,35]. Meanwhile, IGF1 Ec has been found in humans [19], rats [36], and pigs [10] and its roles in muscle repair and regeneration have been the focus of recent studies.…”

Protein Glycosylation Investigated by Mass Spectrometry: An Overview

“…The main aim of glycomics is to understand the structure, enzymatic and biological mechanisms of glycosylation as well as to compare biosystems under normal and pathological conditions [29] in order to figure out glycans alterations as possible biomarkers of a disease. The difficulties caused by microheterogeneity largely prevent a simple and direct approach to investigate the entire set of glycans from glycoproteins after their hydrolysis or by glycoconjugates, and over the years different protocols have been developed [30][31][32][33]. An important aspect in glycoforms micro-heterogenicity molecular structures comprehension relies in their possible different pharmacological profiles [4].…”

“…Other authors lingered on the spike (S) envelope protein of the currently emerging virus (CoV) inducing severe acute respiratory syndrome (SARS) to explain the crucial role of glycoprotein in infection initiation by binding receptor-binding domain of S protein to the cellular receptor ACE2 and in the phase of viral envelope fusion with the host-cell membrane through the endosomal pathway [44]. Actually, the S proteins of coronaviruses display a larger number of N-linked glycan sites (23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38) per protomer but a lower population of oligomannose-type glycans (30%) compared to the other viruses [45]. The increase of the number of glycosylation sites and the reduced density by oligomannose-type glycans seems to be based on an evolutive selection, reflecting a balance between immune evasion by epitope shielding and functionality by attachment to the host cell.…”