Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

The gamma-aminobutyric acidA (GABA)A receptor (GABAR) beta 1 and gamma 2L subtypes have been shown to be phosphorylated in vitro by protein kinase C (PKC) [J. Biol. Chem. 267:14470-14476 (1992); Neuron 12:1081-1095 (1994)]. To determine the physiological consequences of phosphorylation of GABAR isoforms containing the beta 1 and gamma 2L subtypes, the specific serine residues phosphorylated by PKC (beta 1 S409, gamma 2L S327 and S343) were changed to alanines through site-directed mutagenesis. Wild-type (alpha 1 beta 1 gamma 2L GABARs) and three mutant GABAR isoforms [alpha 1 beta 1 gamma 2L(S327A, S343A), alpha 1 beta 1(S409A) gamma 2L, and alpha 1 beta 1(S409A) gamma 2L(S327A, S343A) GABARs) were expressed in mouse L929 fibroblasts through transient cotransfection. Recordings were obtained from each cell with the use of the whole-cell patch-clamp technique. The initial recording was made with the use of control intrapipette solution, and a second recording from the same cell was obtained with pipettes containing either constitutively active PKC [protein kinase M (PKM)] or control solution to obtain paired GABA concentration-response relationships. All GABAR isoforms studied had equivalent maximal GABA currents and similar GABA concentration-response profiles under the control condition. Intracellular PKM treatment increased the maximal current and EC50 value in cells expressing wild-type GABARs. However, PKM reimpalement did not significantly change these parameters in cells expressing any of the mutant GABAR isoforms, indicating that the mutation of either the beta 1 or gamma 2L subtype alone was sufficient to prevent enhancement of GABAR current by PKM. No significant changes were obtained during control reimpalement recordings of wild-type or mutant receptors. Furthermore, PKM treatment did not after the time constants of GABA current desensitization kinetics measured from cells expressing wild-type or mutant receptors. These data thus suggest that PKC phosphorylation of the beta 1 and gamma 2L subtypes enhances GABAR current and that both subtypes are required for complete PKC-mediated enhancement of alpha 1 beta 1 gamma 2L GABAR current.


Journal article


Mol Pharmacol

Publication Date





185 - 195


Alanine, Amino Acid Sequence, Animals, Base Sequence, Cattle, Chloride Channels, DNA Primers, Kinetics, L Cells (Cell Line), Macromolecular Substances, Membrane Potentials, Mice, Molecular Sequence Data, Mutagenesis, Site-Directed, Patch-Clamp Techniques, Phosphorylation, Point Mutation, Protein Kinase C, Protein Multimerization, Receptors, GABA-A, Recombinant Proteins, Serine, Transfection, gamma-Aminobutyric Acid