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Titolo:
An inhibitory segment of the catalytic subunit of phosphorylase kinase does not act as a pseudosubstrate
Autore:
Bartleson, C; Graves, DJ;
Indirizzi:
Iowa State Univ, Dept Biochem Biophys & Mol Biol, Ames, IA 50011 USA Iowa State Univ Ames IA USA 50011 Biophys & Mol Biol, Ames, IA 50011 USA Iowa State Univ, Signal Transduct Training Program, Ames, IA 50011 USA Iowa State Univ Ames IA USA 50011 ct Training Program, Ames, IA 50011 USA
Titolo Testata:
JOURNAL OF BIOLOGICAL CHEMISTRY
fascicolo: 37, volume: 276, anno: 2001,
pagine: 34560 - 34566
SICI:
0021-9258(20010914)276:37<34560:AISOTC>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
DEPENDENT PROTEIN-KINASE; GAMMA-SUBUNIT; REGULATORY SUBUNIT; STRUCTURAL BASIS; SUBSTRATE RECOGNITION; AUTOINHIBITORY DOMAIN; CRYSTAL-STRUCTURE; CALMODULIN; BINDING; TWITCHIN;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
33
Recensione:
Indirizzi per estratti:
Indirizzo: Bartleson, C Iowa State Univ, Dept Biochem Biophys & Mol Biol, 4214 Mol Biol Bldg, Ames, IA 50011 USA Iowa State Univ 4214 Mol Biol Bldg Ames IA USA 50011 0011 USA
Citazione:
C. Bartleson e D.J. Graves, "An inhibitory segment of the catalytic subunit of phosphorylase kinase does not act as a pseudosubstrate", J BIOL CHEM, 276(37), 2001, pp. 34560-34566

Abstract

The C terminus of the catalytic gamma subunit of phosphorylase kinase contains two autoinhibitory calmodulin binding domains designated PhK13 and PhK5. These peptides inhibit truncated gamma (1-300). Previous data show that PhK13 (residues 302-326) is a competitive inhibitor with respect to phosphorylase b, with a K-i of 1.8 muM (1). This result suggests that PhK13 may bind to the active site of truncated gamma (1-300). Variants of PhK13 were prepared to localize the determinants for interaction with the catalytic fragment gamma (1-300). PhK13-1, containing residues 302-312, was found to be acompetitive inhibitor with respect to phosphorylase b with a K-i of 6.0 muM. PhK13 has been proposed to function as a pseudosubstrate inhibitor with Cys-308 occupying the site that normally accommodates the phosphorylatable serine in phosphorylase b. A PhK13-1 variant, C308S, was synthesized. Kinetic characterization of this peptide reveals that it does not serve as a substrate but is a competitive inhibitor. Additional variants were designed based on previous knowledge of phosphorylase kinase substrate determinants. Variants were analyzed as substrates and as inhibitors for truncated gamma (1-300). Although PhK13-1 does not appear to function as a pseudosubstrate, several specificity determinants employed in the recognition of phosphorylase b as substrate are utilized in the recognition of PhK13-1 as an inhibitor.

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Documento generato il 02/12/20 alle ore 16:12:25