title: Phosphoserine as a recognition determinant for glycogen synthase kinase-3: phosphorylation of a synthetic peptide based on the G-component of protein phosphatase-1.
abstract: Prior phosphorylation of its substrate has been shown to be important for substrate recognition by the protein kinase glycogen synthase kinase-3 (GSK-3). Phosphorylation of glycogen synthase by GSK-3 is known to be enhanced by the previous action of casein kinase II and the sequence -SXXXS(P)- was proposed as the minimal recognition determinant for GSK-3. The glycogen binding subunit of type 1 phosphoprotein phosphatase has been shown to be phosphorylated by cyclic AMP-dependent protein kinase at serine-13 in the sequence KPGFS(5)PQPS(9)RRGS(13)ESSEEVYV (F.B. Caudwell, A. Hiraga, and P. Cohen (1986) FEBS Lett. 194, 85-89). Inspection of the sequence revealed potential GSK-3 sites at residues 5 and 9. Using a synthetic peptide with the above sequence, we found that phosphorylation of serine-13 by cyclic AMP-dependent protein kinase permitted the recognition of serine-9 and serine-5 by GSK-3. The work provides another example of a substrate for GSK-3 and demonstrates that the action of GSK-3 is linked to the presence of phosphate in the substrate and not the action of any particular protein kinase. In the course of the analyses, a novel feature of trypsin cleavage of phosphopeptides was noted. In the sequence -SRRGS(P)- trypsin acted uniquely after the first arginine whereas in the sequence -S(P)RRGS(P)- it cleaved randomly at either arginine residue. The fact that GSK-3 could phosphorylate a peptide derived from a phosphatase subunit also raises the possibility that GSK-3 might be involved in controlling glycogen-associated type 1 phosphatase and, more generally, in mediating cyclic AMP control of protein phosphorylation in cells.
authors.affiliation: Department of Biochemistry, Indiana University School of Medicine, Indianapolis 46223.
authors.forename: C J
authors.initials: CJ
authors.lastname: Fiol
authors.forename: J H
authors.initials: JH
authors.lastname: Haseman
authors.forename: Y H
authors.initials: YH
authors.lastname: Wang
authors.forename: P J
authors.initials: PJ
authors.lastname: Roach
authors.forename: R W
authors.initials: RW
authors.lastname: Roeske
authors.forename: M
authors.initials: M
authors.lastname: Kowalczuk
authors.forename: A A
authors.initials: AA
authors.lastname: DePaoli-Roach
mesh_terms: D001120:Arginine / Q000032:analysis; D001665:Binding Sites; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002851:Chromatography, High Pressure Liquid; D038341:Glycogen Synthase Kinases; D006007:Glycogen-Synthase-D Phosphatase / Q000032:analysis*; D007525:Isoelectric Focusing; D010455:Peptides / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D010748:Phosphopeptides / Q000032:analysis; D010749:Phosphoprotein Phosphatases / Q000032:analysis*; D010766:Phosphorylation; D010768:Phosphoserine / Q000032:analysis*; D011494:Protein Kinases / Q000032:analysis*; D054645:Protein Phosphatase 1; D012694:Serine / Q000031:analogs & derivatives*; D013379:Substrate Specificity; D014357:Trypsin
chemical_list: D010455:Peptides; D010710:Phosphates; D010748:Phosphopeptides; D010768:Phosphoserine; D012694:Serine; D001120:Arginine; D011494:Protein Kinases; D038341:Glycogen Synthase Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D006007:Glycogen-Synthase-D Phosphatase; D014357:Trypsin