Identification of three in vivo phosphorylation sites on the glycogen-binding subunit of protein phosphatase 1 from rabbit skeletal muscle, and their response to adrenaline.
The in vivo phosphorylation stoichiometries of 4 serines on the glycogen-binding (G)-subunit of protein phosphatase 1 (PP1) have been determined. In fed rabbits injected with propranolol stoichiometries (mol/mol) were: site 1 (0.67 +/- 0.09), site 2 (0.20 +/- 0.07), site 3a (0.23 +/- 0.01) and site 3b (0). After injection with adrenalin they became: site 1 (0.90 +/- 0.02), site 2 (0.72 +/- 0.01), site 3a (0.23 +/- 0.02) and site 3b (0). These results, together with other data, establish that site 2 phosphorylation by cyclic AMP-dependent protein kinase triggers dissociation of PP1 from the G-subunit in vivo. They also demonstrate that a residue phosphorylated in vitro by glycogen synthase kinase 3 (site 3a) is phosphorylated in vivo.
Dent
P
P
Department of Biochemistry, University of Dundee, Scotland.
Campbell
D G
DG
Caudwell
F B
FB
Cohen
P
P
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D004837:Epinephrine / Q000494:pharmacology*; D006003:Glycogen / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009132:Muscles / Q000201:enzymology*; D010449:Peptide Mapping; D010748:Phosphopeptides / Q000302:isolation & purification; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D011433:Propranolol / Q000494:pharmacology; D054645:Protein Phosphatase 1; D011817:Rabbits; D014357:Trypsin
D046911:Macromolecular Substances; D010748:Phosphopeptides; D006003:Glycogen; D011433:Propranolol; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D014357:Trypsin; D004837:Epinephrine