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Titolo:
PHOSPHORYLATION SPECIFICITIES OF PROTEIN-KINASE-C ISOZYMES FOR BOVINECARDIAC TROPONIN-I AND TROPONIN-T AND SITES WITHIN THESE PROTEINS ANDREGULATION OF MYOFILAMENT PROPERTIES
Autore:
JIDEAMA NM; NOLAND TA; RAYNOR RL; BLOBE GC; FABBRO D; KAZANIETZ MG; BLUMBERG PM; HANNUN YA; KUO JF;
Indirizzi:
EMORY UNIV,SCH MED,DEPT PHARMACOL ATLANTA GA 30322 EMORY UNIV,SCH MED,DEPT PHARMACOL ATLANTA GA 30322 DUKE UNIV,MED CTR,DEPT MED HEMATOL ONCOL DURHAM NC 27710 DUKE UNIV,MED CTR,DEPT CELL BIOL DURHAM NC 27710 CIBA GEIGY LTD,DEPT PHARMACEUT RES,ONCOL K125 CH-4002 BASEL SWITZERLAND NCI,MOL MECHANISMS TUMOR PROMOT SECT,CELLULAR CARCINOGENESIS & TUMOR PROMOT LAB,NIH BETHESDA MD 20892
Titolo Testata:
The Journal of biological chemistry
fascicolo: 38, volume: 271, anno: 1996,
pagine: 23277 - 23283
SICI:
0021-9258(1996)271:38<23277:PSOPIF>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
ACTOMYOSIN MGATPASE ACTIVITY; MUSCLE-CONTRACTION; CA2+-STIMULATED MGATPASE; RECONSTITUTED ACTOMYOSIN; HEAVY-MEROMYOSIN; MYOCARDIAL-CELLS; RAT-HEART; ACTIN; TROPOMYOSIN; EXPRESSION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
42
Recensione:
Indirizzi per estratti:
Citazione:
N.M. Jideama et al., "PHOSPHORYLATION SPECIFICITIES OF PROTEIN-KINASE-C ISOZYMES FOR BOVINECARDIAC TROPONIN-I AND TROPONIN-T AND SITES WITHIN THESE PROTEINS ANDREGULATION OF MYOFILAMENT PROPERTIES", The Journal of biological chemistry, 271(38), 1996, pp. 23277-23283

Abstract

Protein kinase C (PKC) isozymes alpha, delta, epsilon, and zeta, shown to be expressed in adult rat cardiomyocytes, displayed distinct substrate specificities in phosphorylating troponin I and troponin T subunits in the bovine cardiac troponin complex, Thus, because they have different substrate affinities, PKC-alpha, -delta, and -epsilon phosphorylated troponin I more than troponin T, but PKC-zeta conversely phosphorylated the latter more than the former, Furthermore, PKC isozymes exhibited discrete specificities in phosphorylating distinct sites in these proteins as free subunits or in the troponin complex, Unlike otherisozymes, PKC-delta was uniquely able to phosphorylate Ser-23/Ser-24 in troponin I, the bona fide phosphorylation sites for protein kinase A (PKA); and consequently, like PKA, it reduced Ca2+ sensitivity of Ca2+-stimulated MgATPase of reconstituted actomyosin S-1. In addition, PKC-delta, like PKC-alpha, readily phosphorylated Ser-43/Ser-45 (sites common for all PKC isozymes) and reduced maximal activity of MgATPase,In this respect, PKC-delta functioned as a hybrid of PKC-alpha and PKA. In contrast to PKC-alpha, -delta, and -epsilon, PKC-zeta exclusively phosphorylated two previously unknown sites in troponin T. Phosphorylation of troponin T by PKC-alpha resulted in decreases in both Ca2+ sensitivity and maximal activity, whereas phosphorylation by PKC-zeta resulted in a slight increase of the Ca2+ sensitivity without affectingthe maximal activity of MgATPase, Most of the in vitro phosphorylation sites in troponin I and troponin T were confirmed in situ in adult rat cardiomyocytes. The present study has demonstrated for the first time distinct specificities of PKC isozymes for phosphorylation of two physiological substrates in the myocardium, with functional consequences.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 15/07/20 alle ore 08:48:05