Critical Determinants in ER-Golgi Trafficking of Enzymes Involved in Glycosylation

Abstract

All living cells generate structurally complex and compositionally diverse spectra of glycans and glycoconjugates, critical for organismal evolution, development, functioning, defense, and survival. Glycosyltransferases (GTs) catalyze the glycosylation reaction between activated sugar and acceptor substrate to synthesize a wide variety of glycans. GTs are distributed among more than 130 gene families and are involved in metabolic processes, signal pathways, cell wall polysaccharide biosynthesis, cell development, and growth. Glycosylation mainly takes place in the endoplasmic reticulum (ER) and Golgi, where GTs and glycosidases involved in this process are distributed to different locations of these compartments and sequentially add or cleave various sugars to synthesize the final products of glycosylation. Therefore, delivery of these enzymes to the proper locations, the glycosylation sites, in the cell is essential and involves numerous secretory pathway components. This review presents the current state of knowledge about the mechanisms of protein trafficking between ER and Golgi. It describes what is known about the primary components of protein sorting machinery and trafficking, which are recognition sites on the proteins that are important for their interaction with the critical components of this machinery.

Mass Spectrometry-Based Glycoproteomic Workflows for Cancer Biomarker Discovery

“…2 On extracellular and excreted proteins, both N- and O- linked glycosylation often occurs during processing in the ER and Golgi prior to sorting and transport through secretory pathways. 10 – 12 Monosaccharides must be in an activated format such as -UDP, -GDP, or -CMP in order to be transferred to a growing oligosaccharide, lipid, or directly to a protein, but these activated sugars cannot easily pass membranes and must be actively transported into the ER/Golgi, creating another point of potential glycosylation dysregulation. 10 , 13 Both N -and O- glycan modifications have a “core” structure attached to an amino acid side chain which can then be further extended/modified by specific glycosyltransferases.…”

“… 10 – 12 Monosaccharides must be in an activated format such as -UDP, -GDP, or -CMP in order to be transferred to a growing oligosaccharide, lipid, or directly to a protein, but these activated sugars cannot easily pass membranes and must be actively transported into the ER/Golgi, creating another point of potential glycosylation dysregulation. 10 , 13 Both N -and O- glycan modifications have a “core” structure attached to an amino acid side chain which can then be further extended/modified by specific glycosyltransferases. N-linked glycans have a core glycan moiety of two N -acetylglucosamine (GlcNAc) and three mannose residues are generally associated with the amino acid backbone consensus sequences (N-X-S/T, Figure 1 ).…”

Xyloglucan Biosynthesis: From Genes to Proteins and Their Functions

“…As to localization control, small peptide motifs within the N-terminals of GTs may be responsible for transportation and localization throughout the Golgi, localizing each to the correct cisternae. While a signaling peptide has yet to be confirmed for GTs and many plant localized Golgi proteins, yeast and mammalian cells have been thoroughly investigated and suggest plants may share the same machinery ( Zhang and Zabotina, 2022 ).…”

10th Anniversary of Plants—Recent Advances and Further Perspectives

“…are elucidated. This group includes articles [1,2,7,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26], communications [27,28], and review papers [5,6,11,[29][30][31][32][33][34] with significant results applicable both in science and practice. The biology and ecology of plant secondary metabolites, their identification, and biological and therapeutic activity from different aspects of the phytochemistry of edible, aromatic, medicinal, or potentially medicinal plants are represented in a significant number of articles [3,8,[35][36][37][38][39][40][41][42][43][44][45][46][47][48][49], as well as review papers [9,50,<...…”