bims-meglyc Biomed News
on Metabolic disorders affecting glycosylation
Issue of 2023‒03‒26
23 papers selected by
Silvia Radenkovic
Frontiers in Congenital Disorders of Glycosylation Consortium

  1. Curr Gene Ther. 2023 Mar 21.
    Keywords:  Gene therapy; duchenne muscular dystrophy; rare genetic diseases; thalassemia; type I glycogen storage diseases.; viral vectors
  2. Commun Biol. 2023 Mar 23. 6(1): 312
      Human plasma transferrin (Tf) N-glycosylation has been mostly studied as a marker for congenital disorders of glycosylation, alcohol abuse, and hepatocellular carcinoma. However, inter-individual variability of Tf N-glycosylation is not known, mainly due to technical limitations of Tf isolation in large-scale studies. Here, we present a highly specific robust high-throughput approach for Tf purification from human blood plasma and detailed characterization of Tf N-glycosylation on the level of released glycans by ultra-high-performance liquid chromatography based on hydrophilic interactions and fluorescence detection (HILIC-UHPLC-FLD), exoglycosidase sequencing, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). We perform a large-scale comparative study of Tf and immunoglobulin G (IgG) N-glycosylation analysis in two human populations and demonstrate that Tf N-glycosylation is associated with age and sex, along with multiple biochemical and physiological traits. Observed association patterns differ compared to the IgG N-glycome corroborating tissue-specific N-glycosylation and specific N-glycans' role in their distinct physiological functions.
  3. Amino Acids. 2023 Mar 21.
      Glucose-6-phosphatase-α (G6Pase-α) catalyzes the hydrolysis of glucose-6-phosphate to glucose and functions as a key regulator in maintaining blood glucose homeostasis. Deficiency in G6Pase-α causes glycogen storage disease 1a (GSD1a), an inherited disorder characterized by life-threatening hypoglycemia and other long-term complications. We have developed a potential mRNA-based therapy for GSD1a and demonstrated that a human G6Pase-α (hG6Pase-α) variant harboring a single serine (S) to cysteine (C) substitution at the amino acid site 298 (S298C) had > twofold increase in protein expression, resulting in improved in vivo efficacy. Here, we sought to investigate the mechanisms contributing to the increased expression of the S298C variant. Mutagenesis of hG6Pase-α identified distinct protein variants at the 298 amino acid position with substantial reduction in protein expression in cultured cells. Kinetic analysis of expression and subcellular localization in mammalian cells, combined with cell-free in vitro translation assays, revealed that altered protein expression stemmed from differences in cellular protein stability rather than biosynthetic rates. Site-specific mutagenesis studies targeting other cysteines of the hG6Pase-α S298C variant suggest the observed improvements in stability are not due to additional disulfide bond formation. The glycosylation at Asparagine (N)-96 is critical in maintaining enzymatic activity and mutations at position 298 mainly affected glycosylated forms of hG6Pase-α. Finally, proteasome inhibition by lactacystin improved expression levels of unstable hG6Pase-α variants. Taken together, these data uncover a critical role for a single amino acid substitution impacting the stability of G6Pase-α and provide insights into the molecular genetics of GSD1a and protein engineering for therapeutic development.
    Keywords:  Degradation; Glucose metabolism; Glycogen storage disease; Glycosylation; Protein folding
  4. Front Public Health. 2023 ;11 1079601
      Introduction: Rare diseases (RD) are a health priority worldwide, overall affecting hundreds of millions of people globally. Early and accurate diagnosis is essential to support clinical care but remains challenging in many countries, especially the low- and medium-income ones. Hence, undiagnosed RD (URD) account for a significant portion of the overall RD burden.Methods: In October 2020, the Developing Nations Working Group of the Undiagnosed Diseases Network International (DNWG-UDNI) launched a survey among its members, belonging to 20 countries across all continents, to map unmet needs and opportunities for patients with URD. The survey was based on questions with open answers and included eight different domains. Conflicting interpretations were resolved in contact with the partners involved.
    Results: All members responded to the survey. The results indicated that the scientific and medical centers make substantial efforts to respond to the unmet needs of patients. In most countries, there is a high awareness of RD issues. Scarcity of resources was highlighted as a major problem, leading to reduced availability of diagnostic expertise and research. Serious equity in accessibility to services were highlighted both within and between participating countries. Regulatory problems, including securing informed consent, difficulties in sending DNA to foreign laboratories, protection of intellectual property, and conflicts of interest on the part of service providers, remain issues of concern. Finally, most respondents stressed the need to strengthen international cooperation in terms of data sharing, clinical research, and diagnostic expertise for URD patients in low and medium income countries.
    Discussion: The survey highlighted that many countries experienced a discrepancy between the growing expertise and scientific value, the level of awareness and commitment on the part of relevant parties, and funding bodies. Country-tailored public health actions, including general syllabus of medical schools and of the education of other health professionals, are needed to reduce such gaps.
    Keywords:  Undiagnosed Diseases; data sharing; developing nations; rare diseases; survey
  5. Front Cardiovasc Med. 2023 ;10 1137498
      Cardiomyopathy develops through an interaction of genetic and environmental factors. The clinical manifestations of both dilated cardiomyopathy and hypertrophic cardiomyopathy are diverse, but genetic testing defines the causative genes in about half of cases and can predict clinical prognosis. It has become clear that cardiomyopathy is caused not only by single rare variants but also by combinations of multiple common variants, and genome-wide genetic research is important for accurate disease risk assessment. Single-cell analysis research aimed at understanding the pathophysiology of cardiomyopathy is progressing rapidly, and it is expected that genomic analysis and single-cell molecular profiling will be combined to contribute to more detailed stratification of cardiomyopathy.
    Keywords:  dilated cardiomyopathy; genetics; hypertrophic cardiomyopathy; precision medicine; single-cell omics
  6. J Inherit Metab Dis. 2023 Mar 20.
      Medicine development for rare diseases, including inborn errors of metabolism (IEMs) is challenging. Many academic innovations fail to reach the patient, either by stranding in the translational stage or due to suboptimal patient access related to pricing or uncertain effectiveness. Expanding and solidifying the role of the academic in public-private partnerships (PPPs) may present an innovative solution to help overcome these complexities. This narrative review explores the literature on traditional and novel collaborative approaches to medicine development for rare diseases and analyzes examples of PPPs, with a specific focus on IEMs. Several academic institutions have introduced guidelines for socially responsible licensing of innovations for private development. The PPP model offers a more integrative approach towards academic involvement of medicine development. By sharing risks and rewards, failures in the translational stage can be mutually absorbed. If socially responsible terms are not included, however, high pricing can impede patient access. Therefore, we propose a framework for socially responsible PPPs aimed at medicine development for metabolic disorders. This socially responsible PPP framework could stimulate successful and accessible medicine development for IEMs as well as other rare diseases if the establishment of such collaborations includes terms securing joint data ownership and evidence generation, fast access, and socially responsible pricing. This article is protected by copyright. All rights reserved.
    Keywords:  Medicine development; Orphan medicinal products; Public-Private Partnerships; Rare diseases; Socially responsible pricing
  7. Rev Port Cardiol. 2023 Mar 21. pii: S0870-2551(23)00182-8. [Epub ahead of print]
  8. Curr Opin Struct Biol. 2023 Mar 21. pii: S0959-440X(23)00042-8. [Epub ahead of print]80 102568
      Evidence from human genetics supporting the therapeutic hypothesis increases the likelihood that a drug will succeed in clinical trials. Rare and common disease genetics yield a wide array of alleles with a range of effect sizes that can proxy for the effect of a drug in disease. Recent advances in large scale population collections and whole genome sequencing approaches have provided a rich resource of human genetic evidence to support drug target selection. As the range of phenotypes profiled increases and ever more alleles are discovered across world-wide populations, these approaches will increasingly influence multiple stages across the lifespan of a drug discovery programme.
  9. Prog Biophys Mol Biol. 2023 Mar 22. pii: S0079-6107(23)00028-7. [Epub ahead of print]
      Glycometabolism is well known for its roles as the main source of energy, which mainly includes three metabolic pathways: oxidative phosphorylation, glycolysis and pentose phosphate pathway. The orderly progress of glycometabolism is the basis for the maintenance of cardiovascular function. However, upon exposure to harmful stimuli, the intracellular glycometabolism changes or tends to shift toward another glycometabolism pathway more suitable for its own development and adaptation. This shift away from the normal glycometabolism is also known as glycometabolism reprogramming, which is commonly related to the occurrence and aggravation of cardiovascular diseases. In this review, we elucidate the physiological role of glycometabolism in the cardiovascular system and summarize the mechanisms by which glycometabolism drives cardiovascular diseases, including diabetes, cardiac hypertrophy, heart failure, atherosclerosis, and pulmonary hypertension. Collectively, directing GMR back to normal glycometabolism might provide a therapeutic strategy for the prevention and treatment of related cardiovascular diseases.
    Keywords:  Cardiac metabolism; Cardiovascular disease; Glycometabolism reprogramming; Metabolic transformation
  10. Redox Biol. 2023 Mar 14. pii: S2213-2317(23)00073-3. [Epub ahead of print]62 102672
      The transcription factor Nrf2 and its repressor Keap1 mediate cell stress adaptation by inducing expression of genes regulating cellular detoxification, antioxidant defence and energy metabolism. Energy production and antioxidant defence employ NADH and NADPH respectively as essential metabolic cofactors; both are generated in distinct pathways of glucose metabolism, and both pathways are enhanced by Nrf2 activation. Here, we examined the role of Nrf2 on glucose distribution and the interrelation between NADH production in energy metabolism and NADPH homeostasis using glio-neuronal cultures isolated from wild-type, Nrf2-knockout and Keap1-knockdown mice. Employing advanced microscopy imaging of single live cells, including multiphoton fluorescence lifetime imaging microscopy (FLIM) to discriminate between NADH and NADPH, we found that Nrf2 activation increases glucose uptake into neurons and astrocytes. Glucose consumption is prioritized in brain cells for mitochondrial NADH and energy production, with a smaller contribution to NADPH synthesis in the pentose phosphate pathway for redox reactions. As Nrf2 is suppressed during neuronal development, this strategy leaves neurons reliant on astrocytic Nrf2 to maintain redox balance and energy homeostasis.
    Keywords:  Astrocytes; Brain; Glucose metabolism; Mitochondria; NADH; NADPH; Neurons; Nrf2
  11. Mol Ther. 2023 Mar 23. pii: S1525-0016(23)00145-4. [Epub ahead of print]
      The CRISPR/Cas system is commonly known for its ability to cleave DNA in a programmable manner, which has democratized gene editing and facilitated recent breakthroughs in gene therapy. However, newer iterations of the technology using nuclease-disabled Cas enzymes have spurred a variety of different types of genetic engineering platforms such as transcriptional modulation using the CRISPR activation (CRISPRa) and CRISPR interference (CRISPRi) systems. This review introduces the creation of these programmable transcriptional modulators, various methods of delivery utilized for these systems, and recent technological developments. CRISPRa and CRISPRi have also been implemented in genetic screens for interrogating gene function and discovering genes involved in various biological pathways. We describe recent compelling examples of how these tools have become powerful means to unravel genetic networks and uncovering important information about devastating diseases. Finally, we provide an overview of preclinical studies in which transcriptional modulation has been used therapeutically, and we discuss potential future directions of these novel modalities.
  12. Patient. 2023 Mar 22.
      Patient registries fulfill a number of key roles for clinicians, researchers, non-profit organizations, payers, and policy makers. They can help the field understand the natural history of a condition, determine the effectiveness of interventions, measure safety, and audit the quality of care provided. Successful registries in cystic fibrosis, Duchenne's muscular dystrophy, and other rare diseases have become a model for accelerating progress. However, the complex tasks required to develop a modern registry can seem overwhelming, particularly for those who are not from a technical background. In this Education article, a team of co-authors from across patient advocacy, technology, privacy, and commercial perspectives who have worked on a number of such projects offer a "Registry 101" primer to help get started. We will outline the promise and potential of patient registries with worked case examples, identify some of the key technical considerations you will need to consider, describe the type of data you might want to collect, consider privacy risks to protect your users, sketch out some of the paths towards long-term financial sustainability we have observed, and conclude with plans to mitigate some of the challenges that can occur and signpost interested readers to further resources. While rapid growth in the digital health market has presented numerous opportunities to those at the beginning of their journey, it is important to start with the long-term goals in mind and to benefit from the learnings of those who have walked this path before.
  13. Genet Med. 2023 Mar 22. pii: S1098-3600(23)00845-6. [Epub ahead of print] 100832
      PURPOSE: Advances in the study of ultra-rare genetic conditions are leading to the development of targeted interventions developed for single or very small numbers of patients. Due to the experimental but also highly individualized nature of these interventions, they are difficult to classify cleanly as either research or clinical care. Our goal was to understand how parents, IRB members, and clinical geneticists familiar with individualized genetic interventions conceptualize these activities and their implications for the relationship between research and clinical care.METHODS: We conducted qualitative, semi-structured interviews with 28 parents, IRB members, and clinical geneticists, and derived themes from those interviews through content analysis.
    RESULTS: Individuals described individualized interventions as blurring the lines between research and clinical care and focused on hopes for therapeutic benefit and expectations for generalizability of knowledge and benefit to future patients.
    CONCLUSION: Individualized interventions aimed at one or few patients reveal the limitations of a binary framing of research and clinical care. As a hybrid set of activities, individualized interventions suggest the need for flexibility and new frameworks that acknowledge these activities across the spectrum of research and clinical care.
    Keywords:  funding; gene therapy; pediatrics; rare genetic disease; regulatory governance; research and clinical care
  14. BMC Psychiatry. 2023 Mar 24. 23(1): 193
      BACKGROUND: Psychosocial support is a crucial component of adequate rare disease care, but to date psychosocial support needs of this patient population are insufficiently met. Within Q.RARE.LI, we strive to evaluate the effectiveness of a structured, transdiagnostic, and location-independent psychosocial support intervention in routine care of patients with rare autoimmune liver diseases in five countries and prepare its implementation.METHODS: Within an effectiveness-implementation hybrid trial, we aim to a) investigate the effectiveness of the intervention in routine care in five diverse healthcare systems and b) assess implementation outcomes, examine and prepare the implementation context, and develop country-specific implementation strategies. To assess effectiveness, we will include N = 240 patients with rare autoimmune liver diseases. Within a two-armed randomized controlled trial (allocation ratio 1:1), we will compare structured and peer-delivered psychosocial support in addition to care-as-usual (CAU) with CAU alone. Outcomes will be assessed via electronic database entry prior to intervention, directly after, and at a three-month follow-up. Our primary effectiveness outcome will be mental health-related quality of life at post-assessment. Secondary outcomes include depression and anxiety severity, perceived social support, helplessness, and disease acceptance. Implementation outcomes will be assessed within a mixed-methods process evaluation. In a quantitative cross-sectional survey, we will examine perceived acceptability and feasibility in patients, peer-counselors, and healthcare providers involved in delivery of the intervention. In qualitative focus groups, we will analyze the implementation context and determine barriers and facilitators for implementation with different stakeholders (patients and/or representatives, peer-counselors, healthcare providers, health insurers). Based on these results, we will derive country-specific implementation strategies and develop a concrete implementation plan for each country.
    DISCUSSION: The intervention is expected to help patients adjust to their disease and improve their mental quality of life. The transdiagnostic and location-independent program has the potential to reach patients for psychosocial support who are usually hard to reach. By preparing the implementation in five countries, the project can help to make low-threshold psychosocial support available to many patients with rare diseases and improve comprehensive healthcare for an often neglected group.
    Keywords:  Effectiveness-implementation hybrid trial; Liver diseases; Peer-support; Psychosocial support; Psychosomatic medicine; Quality of life; Rare diseases
  15. Biochim Biophys Acta Mol Cell Res. 2023 Mar 17. pii: S0167-4889(23)00033-2. [Epub ahead of print]1870(5): 119462
      Nucleotide sugar transporters (NSTs) are multitransmembrane proteins, localized in the Golgi apparatus and/or endoplasmic reticulum, which provide glycosylation enzymes with their substrates. It has been demonstrated that NSTs may form complexes with functionally related glycosyltransferases, especially in the N-glycosylation pathway. However, potential interactions of NSTs with enzymes mediating the biosynthesis of mucin-type O-glycans have not been addressed to date. Here we report that UDP-galactose transporter (UGT; SLC35A2) associates with core 1 β-1,3-galactosyltransferase 1 (C1GalT1; T-synthase). This provides the first example of an interaction between an enzyme that acts exclusively in the O-glycosylation pathway and an NST. We also found that SLC35A2 associated with the C1GalT1-specific chaperone Cosmc, and that the endogenous Cosmc was localized in both the endoplasmic reticulum and Golgi apparatus of wild-type HEK293T cells. Furthermore, in SLC35A2-deficient cells protein levels of C1GalT1 and Cosmc were decreased and their Golgi localization was less pronounced. Finally, we identified SLC35A2 as a novel molecular target for the antifungal agent itraconazole. Based on our findings we propose that NSTs may contribute to the stabilization of their interaction partners and help them to achieve target localization in the cell, most likely by facilitating their assembly into larger functional units.
    Keywords:  C1GalT1; Cosmc; Golgi apparatus; Mucin-type O-glycans; SLC35A2; UDP-galactose
  16. Fetal Diagn Ther. 2023 Mar 22.
      Skeletal dysplasias (SDs) are a heterogeneous group of heritable disorders that affect development of bone and cartilage. Because each SD is individually rare and because of the heterogeneity within and among disorders, prenatal diagnosis of a specific SD remains challenging. Molecular genetic diagnosis involves invasive testing, which some patients are not amenable to. Further, genetic analysis is time consuming, and results may not become available in time to make pregnancy management decisions. Low-dose fetal CT can aid in the prenatal evaluation of SDs. The main downside is the low but true risk of fetal radiation exposure. As such, fetal CT should only be performed when there is concern for a severe skeletal dysplasia and the diagnosis is in question after a detailed US or if molecular genetic testing is unavailable, and when prenatal diagnosis may affect management or counseling. Fetal CT should be obtained after consultation with geneticists, maternal-fetal medicine specialists and fetal radiologists, and sometimes orthopedic surgeons or neonatologists. The purpose of this article is to review the technique of and indications for fetal CT, as well as discuss fetal radiation risk. Illustrative cases will demonstrate when and how CT may be helpful in the diagnosis of SDs.
  17. Anticancer Agents Med Chem. 2023 Mar 20.
      Neuroprotection is one of the hot topics in medicine. Alzheimer's disease, amyotrophic lateral sclerosis, retinal pigment epithelial (RPE) degeneration, and axonal degeneration have been studied for the involvement of NAD depletion. Localized NAD+ depletion could lead to overactivation and crowding of local NAD+ salvage pathways. It has been stated that NAD+ depletion caused by PARPs and PAR cycling has been related to metabolic diseases and cancer. Additionally, it is now acknowledged that SARM1 dependent NAD+ depletion causes axon degeneration. New targeted therapeutics, such as SARM1 inhibitors, and NAD+ salvage drugs will help alleviate the dysfunctions affecting cell life and death in neurodegeneration as well as in metabolic diseases and cancer.
    Keywords:  ADPR; Cadpr; NADase; Nicotinamide; Sterile ?; TIR; protein-protein interactions.
  18. Phenomics. 2021 Oct;1(5): 229-241
      Cardiovascular diseases (CVDs) are a large group of diseases and have become the leading cause of morbidity and mortality worldwide. Although considerable progresses have been made in the diagnosis, treatment and prognosis of CVD, communication barriers between clinicians and researchers still exist because the phenotypes of CVD are complex and diverse in clinical practice and lack of unity. Therefore, it is particularly important to establish a standardized and unified terminology to describe CVD. In recent years, there have been several studies, such as the Human Phenotype Ontology, attempting to provide a standardized description of the disease phenotypes. In the present article, we outline recent advances in the classification of the major types of CVD to retrospectively review the current progresses of phenotypic studies in the cardiovascular field and provide a reference for future cardiovascular research.
    Keywords:  Cardiovascular disease; Classification; Phenotype; Therapy
  19. Brain. 2023 Mar 22. pii: awad095. [Epub ahead of print]
    Inherited Neuropathy Consortium-Rare Diseases Clinical Research Network (INC-RDCRN)
      Recessive SH3TC2 variants cause Charcot-Marie-Tooth disease type 4C (CMT4C). CMT4C is typically a sensorimotor demyelinating polyneuropathy, marked by early onset spinal deformities, but its clinical characteristics and severity are quite variable. Clear relationships between pathogenic variants and the spectrum of disease manifestations are to date lacking. Gene replacement therapy has been shown to ameliorate the phenotype in a mouse model of CMT4C, emphasizing the need for natural history studies to inform clinical trial readiness. Data, including both genetic information and clinical characteristics, were compiled from the longitudinal, prospective dataset of the Inherited Neuropathy Consortium, a member of the Rare Diseases Clinical Research Network (INC-RDCRN). The Charcot Marie Tooth Neuropathy Score (CMTNS), Examination Score (CMTES) and the Rasch-weighted CMTES (CMTES-R) were used to describe symptoms, neurologic examinations, and neurophysiologic characteristics. Standardized response means were calculated at yearly intervals and a mixed model for repeated measures was used to estimate the change in CMTES and CMTES-R over time. 56 individuals (59% female), median age 27 years (range 2-67 years) with homozygous or compound heterozygous variants in SH3TC2 were identified, including 34 unique variants, 14 of which have not previously been published. 28 participants had longitudinal data available. While there was not a significant difference in the CMTES in those with protein-truncating versus non-protein-truncating variants, there were significant differences in the mean ulnar nerve compound muscle action potential amplitude, the mean radial sensory nerve action potential amplitude, and in the prevalence of scoliosis, suggesting the possibility of a milder phenotype in individuals with one or two non-protein-truncating variants. Overall, the mean value of the CMTES was 13, reflecting moderate clinical severity. There was a high rate of scoliosis (81%), scoliosis surgery (36%), and walking difficulty (94%) among study participants. The CMTES and CMTES-R appeared moderately responsive to change over extended follow-up, demonstrating a standardized response mean of 0.81 standard deviation units or 0.71 standard deviation units respectively, over 3 years. Our analysis represents the largest cross-sectional and only longitudinal study to date, of the clinical phenotype of both adults and children with CMT4C. With the promise of upcoming genetic treatments, this data will further define the natural history of the disease and inform study design in preparation for clinical trials.
    Keywords:  CMT4C; Charcot-Marie-Tooth disease; genotype-phenotype; longitudinal; natural history
  20. Blood Adv. 2023 Mar 23. pii: bloodadvances.2022007084. [Epub ahead of print]
      Changes in surface glycan determinants, specifically sialic acid loss, determine platelet life span. The gradual loss of stored platelet quality is a complex process that fundamentally involves carbohydrate structures. Here, we applied lipophilic extraction and glycan release protocols to sequentially profile N- and O-linked glycans in freshly isolated and seven-day room temperature stored platelet concentrates. Analytical methods including matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), tandem mass spectrometry (MSn), and liquid chromatography (LC) were used to obtain structural details of selected glycans and terminal epitopes. The fresh platelet repertoire of surface structures revealed diverse N-glycans, including high mannose structures, complex glycans with polylactosamine repeats, and glycans presenting blood group epitopes. The O-glycan repertoire was largely comprised of sialylated and fucosylated core-1 and core-2 structures. For both N- and O-linked glycans, we observed a loss in sialylated epitopes with a reciprocal increase in neutral structures as well as increased neuraminidase activity following platelet storage at room temperature. The data indicate that loss of sialylated glycans is associated with diminished platelet quality and untimely removal of platelets following storage.
  21. J Biol Chem. 2023 Mar 22. pii: S0021-9258(23)00271-5. [Epub ahead of print] 104629
      O-GlcNAc transferase (OGT) is an essential glycosylating enzyme that catalyzes the addition of N-acetylglucosamine to serine or threonine residues of nuclear and cytoplasmic proteins. The enzyme glycosylates a broad range of peptide sequences and prediction of glycosylation sites has proven challenging. The lack of an experimentally verified set of polypeptide sequences that are not glycosylated by OGT has made prediction of legitimate glycosylation sites more difficult. Here, we tested a number of intrinsically disordered protein regions as substrates of OGT to establish a set of sequences that are not glycosylated by OGT. The negative data set suggests an amino acid compositional bias for OGT targets. This compositional bias was validated by modifying the amino acid composition of the protein Fused in sarcoma (FUS) to enhance glycosylation. NMR experiments demonstrate that the tetratricopeptide repeat (TPR) region of OGT can bind FUS and that glycosylation-promoting mutations enhance binding. These results provide evidence that the TPR recognizes disordered segments of substrates with particular compositions to promote glycosylation, providing insight into the broad specificity of OGT.
    Keywords:  O-GlcNAc transferase (OGT); O-linked N-acetylglucosamine (O-GlcNAc); Post-translational modification; glycosylation; intrinsically disordered protein; proteomics