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Updated: Dec 21, 2025
Yeast As a Chassis for Developing Functional Assays to Study Human P53
Published on: August 4, 2019
O-linked N-acetylgalactosamine modification is present on the tumor suppressor p53
Zhijue Xu1, Xin Ku1, Azusa Tomioka2
1Key Laboratory of Systems Biomedicine (Ministry of Education) and Collaborative Innovation Center of Systems Biomedicine, Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
Background:
Mucin-type O-glycosylation (referred to as O-GalNAc glycosylation) is the most abundant O-glycosylation on membrane and secretory proteins. Recently several evidences suggest that nuclear or cytoplasmic proteins might also have O-GalNAc glycosylation. However, what nucleocytoplasmic proteins are O-GalNAc glycosylated and what the biological function of this modification in cells are still poorly understood. Previously, we reported the tumor suppressor p53 could be O-GalNAc glycosylated in vitro. To investigate the existence and function of O-GalNAc glycosylation on nucleocytoplasmic proteins in cell, p53 as a representative nucleocytoplasmic protein was studied.
Methods:
Using lectin blotting with GalNAc specific lectins, enzymatic treatments with O-GlcNAcase, core 1 β1, 3-galactosyltransferase and O-glycosidase, and metabolic labeling with un-O-acetylated GalNAz in UDP-Gal/UDP-GalNAc 4-epimerase (GALE) knockout cells, we validated the O-GalNAc glycosylation on p53. Using mass spectrometry analysis and site-directed mutagenesis, we identified the glycosylated sites and studied the functions of O-GalNAc glycosylation on p53.
Results:
The p53 was O-GalNAc glycosylated in cells. Ser121 residue was one of the glycosylated sites on p53. The O-GalNAc glycosylation at Ser121 was associated with the stability and activity of p53.
Conclusions:
These results revealed that the O-GalNAc glycosylation was a novel modification on p53.
General Significance:
Our study provided a pilot evidence that the O-GalNAc glycosylation existed on nucleocytoplasmic protein.
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