Related Experiment Videos
Nucleoplasmic and cytoplasmic glycoproteins.
G W Hart1, R S Haltiwanger, G D Holt
1Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Ciba Foundation Symposium
|January 1, 1989
Summary
Researchers discovered a new protein glycosylation called O-GlcNAc, found in the cell nucleus and cytoplasm. This modification occurs on key proteins involved in gene transcription and nuclear transport, with its exact functions still under investigation.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Protein glycosylation is a crucial post-translational modification.
- O-GlcNAc (O-linked N-acetylglucosamine) is a newly identified form of glycosylation.
- This modification is primarily found in nuclear and cytoplasmic compartments.
Purpose of the Study:
- To describe the novel O-GlcNAc protein glycosylation.
- To identify the enzyme responsible for O-GlcNAc modification.
- To explore the potential functions of O-GlcNAc.
Main Methods:
- Gas-phase protein sequencing was used to analyze O-GlcNAc-modified proteins.
- An assay was developed to detect UDP-GlcNAc:polypeptide O-GlcNAc transferase activity.
- Purification of the glycosyltransferase is underway.
Main Results:
- O-GlcNAc is linked to serine or threonine hydroxyl groups.
- The modification is localized in nuclear and cytoplasmic compartments, including on transcription factors.
- A common structural feature was identified at O-GlcNAc addition sites.
- The O-GlcNAc transferase is membrane-associated, has a cytoplasmic active site, and requires Mn2+.
Conclusions:
- A novel O-GlcNAc protein glycosylation has been characterized.
- The enzyme responsible for this modification has been identified and its properties partially elucidated.
- Potential roles in phosphorylation, complex assembly, and nuclear transport are suggested, warranting further investigation.