title: Determinants for substrate phosphorylation by p21-activated protein kinase (gamma-PAK).
abstract: gamma-PAK, originally designated PAK I and subsequently identified as a member of the p21-activated protein kinase family, has been shown to have cytostatic properties and to be involved in maintaining cells in a nondividing state [Rooney, R. D., et al., (1996) J. Biol. Chem. 271, 21498-21504]. The determinants for phosphorylation of substrates by gamma-PAK have been identified by examining the kinetics of phosphorylation of a series of synthetic peptides patterned after the sequence KKRKSGL, which is the site phosphorylated by gamma-PAK in the Rous sarcoma virus nucleocapsid protein NC in vivo and in vitro. With these peptides, the recognition sequence for gamma-PAK has been shown to contain two basic amino acids in the -2 and -3 positions, as represented by (K/R)RXS, in which the -2 position is an arginine, the -3 position is an arginine or a lysine, and X can be an acidic, basic, or neutral amino acid. A basic amino acid in the -1 or -4 position improves the rate of phosphorylation by increasing the Vmax and decreasing the Km. An acidic amino acid in the -1 position increases the rate (2.5-fold), as does an acidic residue in the -4 position, although to a lower extent (1.6-fold). Proline in the -1 or +1 position has a deleterious effect and inhibits phosphorylation by gamma-PAK. The substrate requirements of protein kinases that recognize basic amino acids on the N-terminal side of the phosphorylatable residue such as cAMP-dependent protein kinase (PKA) and Ca2+/phospholipid-dependent protein kinase (PKC) have been compared with gamma-PAK using the same peptides. An acidic residue in the -1 position negatively affects PKA and PKC; thus, peptides containing the sequence KRES can be used to identify gamma-PAK.
authors.affiliation: Department of Biochemistry, University of California at Riverside, Riverside, California 92521, USA.
authors.forename: P T
authors.initials: PT
authors.lastname: Tuazon
authors.forename: W C
authors.initials: WC
authors.lastname: Spanos
authors.forename: E L
authors.initials: EL
authors.lastname: Gump
authors.forename: C A
authors.initials: CA
authors.lastname: Monnig
authors.forename: J A
authors.initials: JA
authors.lastname: Traugh
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001358:Avian Sarcoma Viruses / Q000737:chemistry; D007700:Kinetics; D019251:Nucleocapsid / Q000737:chemistry / Q000378:metabolism; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011506:Proteins / Q000737:chemistry / Q000378:metabolism; D011817:Rabbits; D012156:Reticulocytes / Q000201:enzymology; D013379:Substrate Specificity; D054462:p21-Activated Kinases
chemical_list: D009842:Oligopeptides; D011506:Proteins; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases