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Detection of Modified Sugar Proteins: Bertozzi

from Chemical and Engineering News

A rapid and efficient chemical strategy has been developed to identify proteins with a mysterious modification--the attachment of oxygen-linked -N-acetylglucosamine (O-GlcNAc) sugars.

O-GlcNAc modification occurs widely on proteins in the nucleus and cytoplasm of multicellular plants and animals. The function of this glycosylation process is poorly understood, but it may play a key role in transcription, cytoskeletal organization, and signaling, and O-GlcNAc metabolism may be abnormally regulated in diabetes.

Tools have been developed recently to aid identification of O-GlcNAc-modified proteins, including site-specific antibodies and a liquid chromatography-tandem mass spectrometry technique. Now, chemistry professor Carolyn R. Bertozzi of Howard Hughes Medical Institute and the University of California, Berkeley, postdoctoral fellow David J. Vocadlo, and coworkers have devised a complementary approach that may prove more useful for high-throughput proteomics applications [Proc. Natl. Acad. Sci. USA, published online July 21, http://www.pnas.org/cgi/content/abstract/1632821100v1].

"We found that O-GlcNAc residues on cellular proteins can be metabolically labeled with azido groups, which primes them for chemical modification via the Staudinger ligation, a reaction we developed a few years back for specific bioconjugation," Bertozzi explains. "Using this chemistry on whole cell lysates, we were able to discriminate proteins modified with O-GlcNAc from the rest of the proteome--setting the stage for an inventory of the complete repertoire of O-GlcNAc-modified proteins.

Related sites:

Carolyn Bertozzi research group

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