# The structure and function of eukaryotic protein glycosylation enzymes

> **NIH NIH R01** · VAN ANDEL RESEARCH INSTITUTE · 2020 · $434,625

## Abstract

Project Summary
Asparagine (N-linked) glycosylation is a ubiquitous modification of eukaryotic secretory and membrane
proteins. N-glycosylation is the most common type of glycosylation, with 90% of glycoproteins being N-
glycosylated. The N-glycans are initially added to a triplet sequence N-X-S/T by a multi-protein transmembrane
complex called oligosaccharyl transferase (OST). Most of the protein N-glycosylation occurs while a protein is
being synthesized by the ribosome and being transported through the translocon. Hence, OST physically
interacts and forms a super-complex with the ribosome and translocon. The mechanisms of protein synthesis
and nascent peptide translocation are better understood thanks to available structures of ribosomes and
translocons. However, our understanding of eukaryotic protein N-glycosylation is very limited due to the lack of
high-resolution OST structures. Our goal is to bridge this major knowledge gap by characterizing the structure
and function of the eight-protein OST complex of yeast. A recent study demonstrated that inhibiting human
OST induces senescence in receptor tyrosine kinase–driven tumor cells, suggesting that OST may be a target
for the development of anti-tumor agents. Furthermore, because transformation of a normal cell to a cancer
cell is usually accompanied by N-glycan branching and extension, several N-glycans have been widely used
as tumor markers: for example, carbohydrate antigen (CA) CA19-9 for detecting pancreatic cancer, and
CA125, which is considered the gold standard marker for diagnosing ovarian cancer. We propose a
comprehensive structure and function study of the yeast OST complex, with a combined approach of cryo-EM,
X-ray crystallography, structure-based mutagenesis and cell biology, and in vitro activity assays. Our work has
important implications in tumorigenesis and cancer diagnosis and treatment.

## Key facts

- **NIH application ID:** 9938510
- **Project number:** 5R01CA231466-03
- **Recipient organization:** VAN ANDEL RESEARCH INSTITUTE
- **Principal Investigator:** Huilin Li
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $434,625
- **Award type:** 5
- **Project period:** 2018-06-18 → 2023-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9938510

## Citation

> US National Institutes of Health, RePORTER application 9938510, The structure and function of eukaryotic protein glycosylation enzymes (5R01CA231466-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9938510. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*