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Diverse Effects of Macromolecular Crowding on the Sequential Glycan‐Processing Pathway Involved in Glycoprotein Quality Control
Author(s) -
Matsushima Hikaru,
Hirano Makoto,
Ito Yukishige,
Totani Kiichiro
Publication year - 2013
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.201300028
Subject(s) - glycan , macromolecular crowding , calreticulin , endoplasmic reticulum , glycoprotein , calnexin , macromolecule , biochemistry , allosteric regulation , mannose , enzyme , protein folding , glycosylation , intracellular , biology , biomolecule , microbiology and biotechnology , chemistry
Abstract Compared with in vitro conditions, the intracellular environment is highly crowded with biomolecules; this has numerous effects on protein functions, including enzymatic activity. We examined the effects of macromolecular crowding on glycan processing of N ‐glycoprotein in the endoplasmic reticulum as a model sequential metabolic pathway. Experiments with synthetic substrates of physiological glycan structure clearly showed that the first half of the pathway (glucose trimming) was accelerated, whereas the second (mannose trimming) was decelerated under molecular crowding conditions. Furthermore, calreticulin, a lectin‐like molecular chaperone, bound more strongly to a glycan‐processing intermediate under these conditions. This study demonstrates the diverse effects of molecular crowding on sequential enzymatic processing, and the importance of the effects of macromolecular crowding on in vitro assays for understanding sequential metabolic pathways.