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Evidence for the Existence of Differential O ‐Glycosylated α 5 ‐Subunits of the γ‐Aminobutyric Acid A Receptor in the Rat Brain
Author(s) -
Sieghart Werner,
Item Chike,
Buchstaller Andrea,
Fuchs Karoline,
Höger Harald,
Adamiker Dieter
Publication year - 1993
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 - 10.1111/j.1471-4159.1993.tb05826.x
Subject(s) - aminobutyric acid , receptor , differential (mechanical device) , chemistry , neuroscience , biology , biophysics , biochemistry , physics , thermodynamics
Polyclonal antibodies were raised to synthetic peptides having amino acid sequences corresponding with the N‐ or C‐terminal part of the γ‐aminobutyric acid A (GABA A ) receptor α 5 ‐subunit. These anti‐peptide α 5 (2–10) or anti‐peptide α 5 (427–433) antibodies reacted specifically with GABA A receptors purified from the brains of 5–10‐day‐old rats in an enzyme‐linked immunosorbent assay and were able to dose‐dependently immunoprecipitate up to 6.3 or 13.1% of the GABA A receptors present in the incubation, respectively. In immunoblots, each of these antibodies reacted with the same two protein bands with apparent molecular mass of 53 or 57 kDa. After exhaustive treatment of purified GABA A receptors with N ‐Glycanase, each of these antibodies identified two proteins with apparent molecular masses of 46 and 48 kDa. Additional treatment of GABA A receptors with neuraminidase and O ‐Glycanase resulted in an apparently single protein with molecular mass of 47 kDa, which again was identified by both the anti‐peptide α 5 (2–10) and the anti‐peptide α 5 (427–433) antibody. These results indicate the existence of at least two different α 5 ‐sub‐units of the GABA A receptor that differ in their carbohydrate content. In contrast to other α‐ or β‐subunits of GABA A receptors so far investigated, at least one of these two α 5 ‐subunits contains O‐linked carbohydrates.