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Titolo:
The phosphoinositide-dependent kinase, PDK-1, phosphorylates conventional protein kinase C isozymes by a mechanism that is independent of phosphoinositide 3-kinase
Autore:
Sonnenburg, ED; Gao, T; Newton, AC;
Indirizzi:
Univ Calif San Diego, Dept Pharmacol, La Jolla, CA 92093 USA Univ Calif San Diego La Jolla CA USA 92093 rmacol, La Jolla, CA 92093 USA
Titolo Testata:
JOURNAL OF BIOLOGICAL CHEMISTRY
fascicolo: 48, volume: 276, anno: 2001,
pagine: 45289 - 45297
SICI:
0021-9258(20011130)276:48<45289:TPKPPC>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
IN-VIVO; PHOSPHATIDYLINOSITOL 3,4,5-TRISPHOSPHATE; DOWN-REGULATION; ACTIVATION; TRANSLOCATION; ALPHA; SITE; ZETA; PKC; AUTOPHOSPHORYLATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
40
Recensione:
Indirizzi per estratti:
Indirizzo: Newton, AC Univ Calif San Diego, Dept Pharmacol, La Jolla, CA 92093 USA Univ Calif San Diego La Jolla CA USA 92093 Jolla, CA 92093 USA
Citazione:
E.D. Sonnenburg et al., "The phosphoinositide-dependent kinase, PDK-1, phosphorylates conventional protein kinase C isozymes by a mechanism that is independent of phosphoinositide 3-kinase", J BIOL CHEM, 276(48), 2001, pp. 45289-45297

Abstract

Phosphorylation by the phosphoinositide-dependent kinase, PDK-1, is required for the activation of diverse members of the AGC family of protein kinases, including the protein kinase C (PKC) isozymes. Here we explore the subcellular location of the PDK-1-mediated phosphorylation of conventional PKCs, and we address whether this phosphorylation is regulated by phosphoinositide 3-kinase. Pulse-chase experiments reveal that newly synthesized endogenous PKC a is primarily phosphorylated in the membrane fraction of COS-7 cells, where it is processed to a species that is phosphorylated at the activation loop and at two carboxyl-terminal positions. This "mature" species is then released into the cytosol. Deletion of the plekstrin homology domain of PDK-1 results in a 4-fold increase in the rate of processing of PKC indicating an autoinhibitory role for this domain. Autoinhibition by the plekstrin homology domain is not relieved by binding 3'-phosphoinositides; PKC is phosphorylated at a similar rate in serum-treated cells and serum-starved cells treated with the phosphoinositide 3-kinase inhibitors, LY294002 and wortmannin. Under the same conditions, the PDK-1-catalyzed phosphorylation ofanother substrate, Akt/protein kinase B, is abolished by these inhibitors. Our data are consistent with a model in which PDK-1 phosphorylates newly synthesized PKC by a mechanism that is independent of 3'-phosphoinositides.

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Documento generato il 09/07/20 alle ore 20:41:34