title: Sphingosine-dependent protein kinase-1, directed to 14-3-3, is identified as the kinase domain of protein kinase C delta.
abstract: Some protein kinases are known to be activated by d-erythro-sphingosine (Sph) or N,N-dimethyl-d-erythro-sphingosine (DMS), but not by ceramide, Sph-1-P, other sphingolipids, or phospholipids. Among these, a specific protein kinase that phosphorylates Ser60, Ser59, or Ser58 of 14-3-3beta, 14-3-3eta, or 14-3-3zeta, respectively, was termed "sphingosine-dependent protein kinase-1" (SDK1) (Megidish, T., Cooper, J., Zhang, L., Fu, H., and Hakomori, S. (1998) J. Biol. Chem. 273, 21834-21845). We have now identified SDK1 as a protein having the C-terminal half kinase domain of protein kinase Cdelta (PKCdelta) based on the following observations. (i). Large-scale preparation and purification of proteins showing SDK1 activity from rat liver (by six steps of chromatography) gave a final fraction with an enhanced level of an approximately 40-kDa protein band. This fraction had SDK1 activity approximately 50000-fold higher than that in the initial extract. (ii). This protein had approximately 53% sequence identity to the Ser/Thr kinase domain of PKCdelta based on peptide mapping using liquid chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry data. (iii). A search for amino acid homology based on the BLAST algorithm indicated that the only protein with high homology to the approximately 40-kDa band is the kinase domain of PKCdelta. The kinase activity of PKCdelta did not depend on Sph or DMS; rather, it was inhibited by these sphingoid bases, i.e. PKCdelta did not display any SDK1 activity. However, strong SDK1 activity became detectable when PKCdelta was incubated with caspase-3, which releases the approximately 40-kDa kinase domain. PKCdelta and SDK1 showed different lipid requirements and substrate specificity, although both kinase activities were inhibited by common PKC inhibitors. The high susceptibility of SDK1 to Sph and DMS accounts for their important modulatory role in signal transduction.
authors.affiliation: Department of Pathobiology, University of Washington, Seattle, Washington 98122-4302, USA.
authors.forename: Akikazu
authors.initials: A
authors.lastname: Hamaguchi
authors.forename: Erika
authors.initials: E
authors.lastname: Suzuki
authors.forename: Kimie
authors.initials: K
authors.lastname: Murayama
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Fujimura
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Hikita
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Iwabuchi
authors.forename: Kazuko
authors.initials: K
authors.lastname: Handa
authors.forename: Donald A
authors.initials: DA
authors.lastname: Withers
authors.forename: Shane C
authors.initials: SC
authors.lastname: Masters
authors.forename: Haian
authors.initials: H
authors.lastname: Fu
authors.forename: Senitiroh
authors.initials: S
authors.lastname: Hakomori
mesh_terms: D048948:14-3-3 Proteins; D000595:Amino Acid Sequence; D000818:Animals; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D020134:Catalytic Domain; D002845:Chromatography; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D050356:Lipid Metabolism; D008099:Liver; D008297:Male; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D011493:Protein Kinase C / Q000378:metabolism*; D051745:Protein Kinase C-delta; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D051381:Rats; D017207:Rats, Sprague-Dawley; D012694:Serine / Q000737:chemistry; D015398:Signal Transduction; D013379:Substrate Specificity; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
chemical_list: D048948:14-3-3 Proteins; D010455:Peptides; D012694:Serine; D014446:Tyrosine 3-Monooxygenase; C497260:Prkcd protein, rat; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases