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Effects of the protein matrix on glycan processing in glycoproteins
Author(s) -
Yet MeiGang,
Shao MingChuan,
Wold Finn
Publication year - 1988
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2.1.3275561
Subject(s) - glycan , golgi apparatus , glycoprotein , endoplasmic reticulum , biochemistry , asparagine , microbiology and biotechnology , biology , fucosylation , endoplasmic reticulum associated protein degradation , chemistry , enzyme , unfolded protein response
In the biosynthesis of glycoproteins containing asparagine‐linked glycans, a number of regulatory factors must be involved in converting the single glycan precursor into the variety of different final structures observed in different eukaryotic species. Among these factors are the kind of glycan‐processing enzymes available in the Golgi apparatus of differenct cells, the specificity and regulatory properties of these enzymes, and the unique properties of the protein matrix in which a given glycan resides during the biosynthetic processing. In examining the role of this latter regulatory factor, we have considered a simplified model in which a few key steps are common to all cells, regardless of the nature of the processing enzymes available. The protein‐bound oligomannose precursor Man 8 GlcNAc 2 ‐, arriving in the Golgi after the initial trimming in the endoplasmic reticulum (ER), first undergoes a series of preprocessing steps to yield Man 5 GlcNAc 2 ‐in animals and plants or Man 13‐15 GlcNAc 2 ‐ in yeast. At this stage the key commitment step — to process or not to process—determines whether the above intermediates will remain as unprocessed oligomannose structures or be initiated into a new series of reactions to yield processed structures characteristic of the organisms involved (complex or hybrid for vertebrates, polymannose for yeast, xylosylated glycans for plants and some invertebrates, or Man 3 GlcNAc 2 ‐ structures for other invertebrates). It is proprosed that this commitment step, along with the obligatory preprocessing steps, is regulated primarily by each glycan's unique exposure on its protein matrix. Subsequent processing steps leading to complex or hybrid structures, fucosylation, extent of branching, and specific structures at the nonreducing terminals are most likely determined primarily by the enzyme makeup of the individual processing machineries, but with the protein matrix still playing a significant role.—Y et , M.‐G.; S hao , M.‐C.; W old , F. Effects of the protein matrix on glycan processing in glycoproteins. FASEB J. 2: 22‐31; 1988.