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Contributions of N‐Linked Glycosylation to the Expression of a Functional α7‐Nicotinic Receptor in Xenopus Oocytes
Author(s) -
Chen Dag,
Dang Hong,
Patrick James W.
Publication year - 1998
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1998.70010349.x
Subject(s) - xenopus , glycosylation , asparagine , n linked glycosylation , biology , receptor , nicotinic acetylcholine receptor , acetylcholine receptor , protein subunit , glycoprotein , biochemistry , microbiology and biotechnology , nicotinic agonist , amino acid , gene , glycan
The α7 subunit of the neuronal nicotinic acetylcholine receptor, when expressed in Xenopus oocytes, forms homooligomeric ligand‐gated ion channels that are blocked by a snake toxin, α‐bungarotoxin. The amino‐terminal extracellular domain of the α7 sequence has three consensus sites for asparagine‐linked glycosylation (N46DS, N90MS, and N133AS). In this study, we show that α7 expressed either in vivo or in vitro is a glycoprotein of 57 kDa. In addition, we demonstrate by site‐directed mutagenesis that all three consensus sites are used for glycosylation. To elucidate the role(s) of asparagine‐linked glycosylation in the formation and function of the α7 receptor, wild‐type and glycosylation‐deficient α7 subunits were expressed in COS cells and oocytes. We examined biochemical and physiological properties of expressed receptors and found that α7 glycosylation mutations do not affect homooligomerization and surface protein expression of the α7 receptor but do affect surface expression of α‐bungarotoxin binding sites and the function of the receptor. Our data indicate that asparagine‐linked glycosylation is required for the expression of a functional α7 receptor in oocytes.