Activation of hepatic adenylate cyclase by guanyl nucleotides. Modeling of the transient kinetics suggests an 'excited' state of GTPase is a control component of the system

M. S. Rendell, M. Rodbell, M. Berman

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

A three-state model developed originally from analysis of the steady state kinetics of hepatic adenylate cyclase has been extended to account for the transient kinetics of activation by guanyl-5'-yl imidodiphosphate (Gpp(NH)p). In contrast to activation by Gpp(NH)p, activation of the enzyme by GTP proceeds not only without a lag phase but is of considerably lower magnitude. These differences between Gpp(NH)p and GTP can be explained by the hypothesis that GTP is hydrolyzed at the nucleotide regulatory site(s) associated with adenylate cyclase and that GTPase activity is revealed uniquely when the enzyme system is in its state of highest adenylate cyclase activity. With this hypothesis, the characteristics of activation by GTP could be simulated. The implications of this model are discussed with respect to the actions of hormones and cholera toxin on adenylate cyclase activity.

Original languageEnglish
Pages (from-to)7909-7912
Number of pages4
JournalJournal of Biological Chemistry
Volume252
Issue number22
StatePublished - 1977
Externally publishedYes

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Guanylyl Imidodiphosphate
GTP Phosphohydrolases
Guanosine Triphosphate
Adenylyl Cyclases
Excited states
Nucleotides
Chemical activation
Kinetics
Liver
Enzyme Activation
Cholera Toxin
Enzymes
Hormones

All Science Journal Classification (ASJC) codes

  • Biochemistry

Cite this

Activation of hepatic adenylate cyclase by guanyl nucleotides. Modeling of the transient kinetics suggests an 'excited' state of GTPase is a control component of the system. / Rendell, M. S.; Rodbell, M.; Berman, M.

In: Journal of Biological Chemistry, Vol. 252, No. 22, 1977, p. 7909-7912.

Research output: Contribution to journalArticle

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