UMMS Affiliation

Department of Biochemistry and Molecular Pharmacology

Publication Date


Document Type



Animals; Endoplasmic Reticulum; Eukaryotic Cells; *Evolution, Molecular; Glycosylation; Hexosyltransferases; Humans; Membrane Proteins; Metabolic Diseases; *Protein Modification, Translational; Yeasts


Biochemistry | Pharmacology, Toxicology and Environmental Health


Asparagine-linked glycosylation (ALG) is one of the most common protein modification reactions in eukaryotic cells, as many proteins that are translocated across or integrated into the rough endoplasmic reticulum (RER) carry N-linked oligosaccharides. Although the primary focus of this review will be the structure and function of the eukaryotic oligosaccharyltransferase (OST), key findings provided by the analysis of the archaebacterial and eubacterial OST homologues will be reviewed, particularly those that provide insight into the recognition of donor and acceptor substrates. Selection of the fully assembled donor substrate will be considered in the context of the family of human diseases known as congenital disorders of glycosylation (CDG). The yeast and vertebrate OST are surprisingly complex hetero-oligomeric proteins consisting of seven or eight subunits (Ost1p, Ost2p, Ost3p/Ost6p, Ost4p, Ost5p, Stt3p, Wbp1p, and Swp1p in yeast; ribophorin I, DAD1, N33/IAP, OST4, STT3A/STT3B, Ost48, and ribophorin II in mammals). Recent findings from several laboratories have provided overwhelming evidence that the STT3 subunit is critical for catalytic activity. Here, we will consider the evolution and assembly of the eukaryotic OST in light of recent genomic evidence concerning the subunit composition of the enzyme in diverse eukaryotes.

DOI of Published Version



Glycobiology. 2006 Apr;16(4):47R-62R. Epub 2005 Nov 29. Link to article on publisher's site

Journal/Book/Conference Title

Glycobiology glycotransferase)

Related Resources

Link to Article in PubMed

PubMed ID




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