title: Phosphorylation of Rho-associated kinase (Rho-kinase/ROCK/ROK) substrates by protein kinases A and C.
abstract: Rho-associated kinase (Rho-kinase/ROCK/ROK) is a serine/threonine kinase and plays an important role in various cellular functions. The cAMP-dependent protein kinase (protein kinase A/PKA) and protein kinase C (PKC) are also serine/threonine kinases, and directly and/or indirectly take part in the signal transduction pathways of Rho-kinase. They have similar phosphorylation site motifs, RXXS/T and RXS/T. The purpose of this study was to identify whether sites phosphorylated by Rho-kinase could be targets for PKA and PKC and to find peptide substrates that are specific to Rho-kinase, i.e., with no phosphorylation by PKA and PKC. A total of 18 substrates for Rho-kinase were tested for phosphorylation by PKA and PKC. Twelve of these sites were easily phosphorylated. These results mean that Rho-kinase substrates can be good substrates for PKA and/or PKC. On the other hand, six Rho-kinase substrates showing no or very low phosphorylation efficiency (<20%) for PKA and PKC were identified. Kinetic parameters (K(m) and k(cat)) showed that two of these peptides could be useful as substrates specific to Rho-kinase phosphorylation.
authors.affiliation: CREST, Japan Science and Technology Corporation, Japan.
authors.forename: Jeong-Hun
authors.initials: JH
authors.lastname: Kang
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Jiang
authors.forename: Riki
authors.initials: R
authors.lastname: Toita
authors.forename: Jun
authors.initials: J
authors.lastname: Oishi
authors.forename: Kenji
authors.initials: K
authors.lastname: Kawamura
authors.forename: Aishan
authors.initials: A
authors.lastname: Han
authors.forename: Takeshi
authors.initials: T
authors.lastname: Mori
authors.forename: Takuro
authors.initials: T
authors.lastname: Niidome
authors.forename: Masami
authors.initials: M
authors.lastname: Ishida
authors.forename: Kenji
authors.initials: K
authors.lastname: Tatematsu
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Tanizawa
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Katayama
mesh_terms: D020816:Amino Acid Motifs; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013379:Substrate Specificity; D054460:rho-Associated Kinases
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C