Phosphorylation of the GABAA receptor by cAMP-dependent protein kinase and by protein kinase C: analysis of the substrate domain.
Previous work has shown that the GABAA-receptor (GABAA-R) could be phosphorylated by cAMP-dependent protein kinase (PKA), protein kinase C (PKC), and a receptor associated kinase. However, no clear picture has yet emerged concerning the particular subunit/subtypes of the GABAA-R that were phosphorylated by PKA and PKC. In the present report we show that an antibody raised against a 23 amino acid polypeptide corresponding to a sequence in the putative intracellular loop of the beta 1 subunit of the receptor blocks the in vitro phosphorylation of the purified receptor by PKA and PKC. Moreover, N-terminal sequence analysis of the principal phosphopeptide fragment obtained after proteolysis of the receptor yielded a sequence that corresponds to the beta 3 subunit of the receptor. Such data provide additional support for our hypothesis (Browning et al., 1990, Proc. Natl. Acad. Sci. USA 87:1315-1317) that both PKA and PKC phosphorylate the beta-subunit of the GABAA-R.
Department of Pharmacology, University of Colorado Health Sciences Center, Denver 80222.
M D
MD
Browning
S
S
Endo
G B
GB
Smith
E M
EM
Dudek
R W
RW
Olsen
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D001665:Binding Sites; D002417:Cattle; D016384:Consensus Sequence; D000242:Cyclic AMP / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009206:Myocardium / Q000201:enzymology; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*; D011963:Receptors, GABA-A / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000378:metabolism
D000906:Antibodies; D010446:Peptide Fragments; D011963:Receptors, GABA-A; D000242:Cyclic AMP; D011494:Protein Kinases; D011493:Protein Kinase C; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase