Characterization of the regulatory domain of the gamma-subunit of phosphorylase kinase. The two noncontiguous calmodulin-binding subdomains are also autoinhibitory.

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Publication Type Journal Article
School or College College of Pharmacy; School of Medicine
Department Biomedical Informatics; Biochemistry; Pharmacology & Toxicology
Creator Blumenthal, Donald K.
Other Author Dasgupta, Maltrayee
Title Characterization of the regulatory domain of the gamma-subunit of phosphorylase kinase. The two noncontiguous calmodulin-binding subdomains are also autoinhibitory.
Date 1995-09-22
Description Phosphorylase kinase is a multimeric protein kinase (alpha 4 beta 4 gamma 4 delta 4) whose enzymatic activity is conferred by its gamma-subunit. A library of 18 overlapping synthetic peptides spanning residues 277-386 of the gamma-subunit has been prepared to use in identifying important regulatory structures in the protein. In the present study, the library was screened to identify regions that might function as autoinhibitory domains. Peptides from two distinct regions were found to inhibit the Ca2(+)-activated holoenzyme. The same regions were previously found to bind calmodulin (i.e. the delta-subunit; Dasgupta, M. Honeycutt, T., and Blumenthal, D. K. (1989) J. Biol. Chem. 264, 17156-17163). The most potent substrate antagonist peptides were PhK13 (residues 302-326; Ki = 300 nM) and PhK5 (residues 342-366; Ki = 20 microM). Both peptides inhibited the holoenzyme competitively with respect to phosphorylase b and noncompetitively with respect to Mg.ATP. When the pattern of inhibition with both peptides present was analyzed, inhibition was observed to be synergistic and modestly cooperative indicating that the two peptides can simultaneously occupy the protein substrate-binding site(s). These data are consistent with a model in which the regions of the gamma-subunit represented by PhK5 and PhK13 work in concert as regulatory subdomains that transduce Ca2(+)-induced conformational changes in the delta-subunit to the catalytic gamma-subunit through a pseudosubstrate autoinhibitory mechanism.
Type Text
Publisher American Society for Biochemistry and Molecular Biology (ASBMB)
Volume 270
Issue 38
First Page 22283
Last Page 22289
Subject Metabolism; Phosphorylase Kinase
Subject MESH Amino Acid Sequence; Binding Sites; Calmodulin-Binding Proteins; Kinetics; Molecular Sequence Data; Peptides; Chemistry; Pharmacology; Phosphorylase Kinase
Language eng
Bibliographic Citation Dasgupta M, Blumenthal DK. Characterization of the regulatory domain of the gamma-subunit of phosphorylase kinase. The two noncontiguous calmodulin-binding subdomains are also autoinhibitory. J Biol Chem. 1995 Sep 22;270(38):22283-9. Retrieved on September 13, 2006 from http://content.lib.utah.edu/cgi-bin/admin/add.exe?CISODB=/ir-main
Rights Management Copyright © American Society for Biochemistry and Molecular Biology, J Biol Chem., 270, 22283-9, 1995.
Format Medium application/pdf
Identifier ir-main,389
ARK ark:/87278/s67s8621
Setname ir_uspace
Date Created 2012-06-13
Date Modified 2012-06-13
ID 704103
Reference URL https://collections.lib.utah.edu/ark:/87278/s67s8621
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