• Molecules and Cells
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• v.46 no.6
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• pp.337-344
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• 2023

N-glycosylation, a common post-translational modification, is widely acknowledged to have a significant effect on protein stability and folding. N-glycosylation is a complex process that occurs in the endoplasmic reticulum (ER) and requires the participation of multiple enzymes. GlcNAc-1-P-transferase (GPT) is essential for initiating N-glycosylation in the ER. Tunicamycin is a natural product that inhibits N-glycosylation and produces ER stress, and thus it is utilized in research. The molecular mechanism by which GPT triggers N-glycosylation is discussed in this review based on the GPT structure. Based on the structure of the GPT-tunicamycin complex, we also discuss how tunicamycin reduces GPT activity, which prevents N-glycosylation. This review will be highly useful for understanding the role of GPT in the N-glycosylation of proteins, as well as presents a potential for considering tunicamycin as an antibiotic treatment.

• BMB Reports
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• v.44 no.12
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• pp.765-771
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• 2011

Cancer treatment has been stratified by companion biomarker tests that serve to provide information on the genetic status of cancer patients and to identify patients who can be expected to respond to a given treatment. This stratification guarantees better efficiency and safety during treatment. Cancer patients, however, marginally benefit from the current companion biomarker-aided treatment regimens, presumably because companion biomarker tests are dependent solely on the mutation status of several genes status quo. In the true sense of the term, "personalized medicine", cancer patients are deemed to be identified individually by their molecular signatures, which are not necessarily confined to genetic mutations. Glycosylation is tremendously dynamic and shows alterations in cancer. Evidence is accumulating that aberrant glycosylation contributes to the development and progression of cancer, holding the promise for use of glycosylation status as a companion biomarker in cancer treatment. There are, however, several challenges derived from the lack of a reliable detection system for aberrant glycosylation, and a limited library of aberrant glycosylation. The challenges should be addressed if glycosylation status is to be used as a companion biomarker in cancer treatment and contribute to the fulfillment of personalized medicine.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.5
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• pp.914-919
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• 1997

We investigated the effects of vitamin E supplementation on the protein glycosylation in vivo. Weaned KK-mice were fed high fat diet containing 20% corn oil(wt/wt), and sacrificed at 4, 6, and 0 months of age. High vitamin E diet was the high fat diet supplemented with an excess amount of 이-$\alpha$-tocopheryl acetate(2080IU/kg diet). We measured $HbA_{1C}$ as a glycosylation early product, and collagen-linked fluorescence (CLF) of skin as a glycosylation and product. We found that diabetic group had increased levels of $HbA_{1C}$ within 2 months after onset of diabetes and during the experiments. The skin CLF increased dramatically 5 months after onset of diabetics. Treatment with vitamin E did not modify the level of blood glucose. However, we observed a significant lowering in CLF and $HbA_{1C}$ in diabetic mice.

• Clinical and Experimental Reproductive Medicine
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• v.42 no.3
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• pp.77-85
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• 2015

One of the key factors of early development is the specification of competence between the oocyte and the sperm, which occurs during gametogenesis. However, the starting point, growth, and maturation for acquiring competence during spermatogenesis and oogenesis in mammals are very different. Spermatogenesis includes spermiogenesis, but such a metamorphosis is not observed during oogenesis. Glycosylation, a ubiquitous modification, is a preliminary requisite for distribution of the structural and functional components of spermatids for metamorphosis. In addition, glycosylation using epididymal or female genital secretory glycans is an important process for the sperm maturation, the acquisition of the potential for fertilization, and the acceleration of early embryo development. However, nonemzymatic unexpected covalent bonding of a carbohydrate and malglycosylation can result in falling fertility rates as shown in the diabetic male. So far, glycosylation during spermatogenesis and the dynamics of the plasma membrane in the process of capacitation and fertilization have been evaluated, and a powerful role of glycosylation in spermatogenesis and early development is also suggested by structural bioinformatics, functional genomics, and functional proteomics. Further understanding of glycosylation is needed to provide a better understanding of fertilization and embryo development and for the development of new diagnostic and therapeutic tools for infertility.

• Genomics & Informatics
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• v.6 no.4
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• pp.223-226
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• 2008

We introduce a computational approach for analysis of glycosylation in Post-PKS tailoring steps. It is a computational method to predict the deoxysugar biosynthesis unit pathway and the substrate specificity of glycosyltransferases involved in the glycosylation of polyketides. In this work, a directed and weighted graph is introduced to represent and predict the deoxysugar biosynthesis unit pathway. In addition, a homology based gene clustering method is used to predict the substrate specificity of glycosyltransferases. It is useful for the rational design of polyketide natural products, which leads to in silico drug discovery.

• KSBB Journal
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• v.16 no.1
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• pp.82-86
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• 2001

Glyco-acrylate and methacrylate were synthesized by lipase-catalyzed glycosylation of acrylic acid, methacrylic acid and their vinyl esters with $\beta$-methyl fructoside and glycerol in t-butanol as a reaction medium. At the optimum conditions for enzymatic glycosylation of acrylic acid and vinyl methacrylate, we attained up to 80% conversion for glyco-acrylate from acrylic acid and 90% conversion for glyco-methacrylate from vinyl methacrylate. The polymerizable glyco-acrylates and methacrylate have biomedical application as hydrophilic monomers and hydration modifiers to be use for hydrogel contact lens formulation.

• Proceedings of the KSAR Conference
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• 2002.06a
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• pp.21-21
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• 2002

사람의 erythropoietin (hEPO) 는 산성 당단백질 호르몬이며 적혈구 생산의 주요조절인자로서 적혈구의 분화와 hemoglobin (Hb) 형성을 촉진하여 빈혈치료제로 이용된다. 사람 EPO 는 166개 아미노산으로 구성되어 있으며, 24, 38, 83 번 아미노산은 N-glycosylation에 의해, 126 번 아미노산은 O-glycosylation에 의해 변형되며, 특히 N-glycosylation은 hEPO 의 세포외 분비 및 활성에 관여한다고 보고된 바 있다. (중략)

• YAKHAK HOEJI
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• v.57 no.4
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• pp.250-257
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• 2013

Biosimilars are important drugs in medicine and contain many glycosylated proteins. Thorough analysis of the glycosylated protein is a prerequisite for evaluation of biosimilar glycan drugs. A method to assess the diversity of N-glycosylation sites and N-glycans from biosimilar glycan drugs has been developed using two separate methods, LC-MS/MS and MALDI-TOF MS, respectively. Development of sensitive, accurate, and efficient methods for evaluation of glycoproteins is still needed. In this study, analysis of both N-glycosylation sites and N-glycans of glycoprotein was performed using the same LC-MS/MS with two different nano-LC columns, nano-C18 and nano-porous graphitized carbon (nano-PGC) columns. N-glycosylated proteins, including RNAse B (one N-glycosylation site), Fetuin (three sites), and ${\alpha}$-1 acid glycoprotein (four sites), were used, and small amounts of each protein were used for identification of N-glycosylation sites. In addition, high mannose N-glycans (one type of typical glycan structure), Mannose 5 and 9, eluted from RNAse B, were successfully identified using nano-PGC-LC MS/MS analysis, and the abundance of each glycan from the glycoprotein was calculated. This study demonstrated an accurate and efficient method for determination of N-glycosylation sites and N-glycans of glycoproteins based on high sensitive LC-MS/MS using two different nano-columns; this method could be applied for evaluation of the quality of various biosimilar drugs containing N-glycosylation groups.

• Journal of Microbiology and Biotechnology
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• v.30 no.9
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• pp.1297-1304
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• 2020

Elevated serum levels of alpha-1-acid glycoprotein (AGP) are known to be associated with several types of cancer. In addition, some reports have indicated that changes in glycosylation of AGP are associated with cancer progression. However, changes in AGP levels of serum and changes in glycosylation of AGPs in breast cancer have not been specifically studied. In the present study, serum AGP levels in benign (BN) cancer and breast cancer stage I (BC I), BC IIA, BC IIB, and BC III in Korean women were measured using an enzyme-linked immunosorbent assay (ELISA). AGP was purified from individual sera by hot phenol extraction and then subjected to AGP glycosylation analysis. Three types of AGP glycosylation (fucosylation, high-mannose-type and sialylation) were detected using enzyme-linked lectin assays (ELLAs). Serum AGP levels were higher in BC I, BC IIA, BC IIB, and BC III, than in the BN group, and the level in BC I and BC IIA was high enough to be distinguished from BN. Meanwhile, terminal fucosylation and high-mannose-type glycans appeared to be lowest in BC I. The glycosylation levels of BC I provide sensitivity and specificity that make BC I clearly distinguishable from BC IIA, BC IIB, and BC III as well as BN. Therefore, determination of serum AGP or AGP glycosylation level could be useful for detecting the early stages of breast cancer.

• Development and Reproduction
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• v.25 no.4
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• pp.199-211
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• 2021

Equine chorionic gonadotropin (eCG), produced by the endometrial cups of the placenta after the first trimester, is a specific glycoprotein that displays dual luteinizing hormone (LH)-like and follicle-stimulating hormone (FSH)-like effects in non-equid species. However, in equidaes, eCG exhibits only LH-like activity. To identify the specific biological functions of glycosylated sites in eCG, we constructed the following site mutants of N- and O-linked glycosylation: eCGβ/αΔ56, substitution of α-subunit⁵⁶ N-linked glycosylation site; eCGβ-D/α, deletion of the O-linked glycosylation sites at the β-subunit, and eCGβ-D/αΔ56, double mutant. We produced recombinant eCG (rec-eCG) proteins in Chinese hamster ovary suspension (CHO-S) cells. We examined the biological activity of rec-eCG proteins in CHO-K1 cells expressing the eLH/CG receptor and found that signal transduction activities of deglycosylated mutants remarkably decreased. The EC₅₀ levels of eCGβ/αΔ56, eCGβ-D/α, and eCGβ-D/αΔ56 mutants decreased by 2.1-, 5.6-, and 3.4-fold, respectively, compared to that of wild-type eCG. The Rmax values of the mutants were 56%-80% those of wild-type eCG (141.9 nmol/10⁴ cells). Our results indicate that the biological activity of eCG is greatly affected by the removal of N- and O-linked glycosylation sites in cells expressing eLH/CGR. These results provide important information on rec-eCG in the regulation of specific glycosylation sites and improve our understanding of the specific biological activity of rec-eCG glycosylation sites in equidaes.