Rapamycin-sensitive phosphorylation of PKC on a carboxy-terminal site by an atypical PKC complex
| Autor: | Davey B. Parekh, J.J. Kelly, M. Frech, Richard D. H. Whelan, J.A. Le Good, Brian A. Hemmings, Wolfgang H. Ziegler, Peter J. Parker |
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| Rok vydání: | 1999 |
| Předmět: |
Morpholines
Allosteric regulation Biology General Biochemistry Genetics and Molecular Biology Cell Line Substrate Specificity chemistry.chemical_compound Serine Animals Humans LY294002 Binding site Kinase activity Enzyme Inhibitors Phosphorylation Protein kinase C Protein Kinase C Phosphoinositide-3 Kinase Inhibitors Sirolimus Binding Sites Agricultural and Biological Sciences(all) Biochemistry Genetics and Molecular Biology(all) Kinase Transfection Molecular biology Cell biology Rats chemistry Chromones General Agricultural and Biological Sciences |
| Zdroj: | Current biology : CB. 9(10) |
| ISSN: | 0960-9822 |
| Popis: | The protein kinase C (PKC) family has been implicated in the control of many cellular functions. Although PKC isotypes are characterized by their allosteric activation, phosphorylation also plays a key role in controlling activity. In classical PKC isotypes, one of the three critical sites is a carboxy-terminal hydrophobic site also conserved in other AGC kinase subfamily members. Although this site is crucial to the control of this class of enzymes, the upstream kinase(s) has not been identified.A membrane-associated kinase activity that phosphorylates the hydrophobic site in PKCalpha was detected. This activity was suppressed when cells were pretreated with the immunosuppresant drug rapamycin or the phosphoinositide (Pl) 3-kinase inhibitor LY294002. These pretreatments also blocked specifically the serum-induced phosphorylation of the hydrophobic site in PKCdelta in vivo. The most highly purified hydrophobic site kinase preparations ( approximately 10,000-fold) reacted with antibodies to PKCzeta/iota. Consistent with this, rapamycin and LY294002 reduced the recovery of PKCzeta from the membrane fraction of transfected cells. An activated mutant of PKCzeta, but not wild-type PKCzeta, induced phosphorylation of the PKCdelta hydrophobic site in a rapamycin-independent manner, whereas a kinase-dead PKCzeta mutant suppressed this serum-induced phosphorylation. The immunopurified, activated mutant of PKCzeta could phosphorylate the PKCdelta hydrophobic site in vitro, whereas wild-type PKCzeta could not.PKCzeta is identified as a component of the upstream kinase responsible for the phosphorylation of the PKCdelta hydrophobic site in vitro and in vivo. PKCzeta can therefore control the phosphorylation of this PKCdelta site, antagonizing a rapamycin-sensitive pathway. |
| Databáze: | OpenAIRE |
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