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Record 10 of 3489
Plant chimeric Ca2+/Calmodulin-dependent protein kinase. Role of the neural visinin-like domain in regulating autophosphorylation and calmodulin affinity
External Online Source: doi:10.1074/jbc.M000771200
Author and Affiliation:
Sathyanarayanan, P. V.(Washington State University, Laboratory of Plant Molecular Biology and Physiology, Department of Horticulture, Pullman, Washington 99164-6414, United States)
Cremo, C. R.
Poovaiah, B. W.
Abstract: Chimeric Ca(2+)/calmodulin-dependent protein kinase (CCaMK) is characterized by a serine-threonine kinase domain, an autoinhibitory domain, a calmodulin-binding domain and a neural visinin-like domain with three EF-hands. The neural visinin-like Ca(2+)-binding domain at the C-terminal end of the CaM-binding domain makes CCaMK unique among all the known calmodulin-dependent kinases. Biological functions of the plant visinin-like proteins or visinin-like domains in plant proteins are not well known. Using EF-hand deletions in the visinin-like domain, we found that the visinin-like domain regulated Ca(2+)-stimulated autophosphorylation of CCaMK. To investigate the effects of Ca(2+)-stimulated autophosphorylation on the interaction with calmodulin, the equilibrium binding constants of CCaMK were measured by fluorescence emission anisotropy using dansylated calmodulin. Binding was 8-fold tighter after Ca(2+)-stimulated autophosphorylation. This shift in affinity did not occur in CCaMK deletion mutants lacking Ca(2+)-stimulated autophosphorylation. A variable calmodulin affinity regulated by Ca(2+)-stimulated autophosphorylation mediated through the visinin-like domain is a new regulatory mechanism for CCaMK activation and calmodulin-dependent protein kinases. Our experiments demonstrate the existence of two functional molecular switches in a protein kinase regulating the kinase activity, namely a visinin-like domain acting as a Ca(2+)-triggered switch and a CaM-binding domain acting as an autophosphorylation-triggered molecular switch.
Publication Date: Sep 29, 2000
Document ID:
20040141541
(Acquired Nov 09, 2004)
Subject Category: LIFE SCIENCES (GENERAL)
Document Type: Journal Article
Publication Information: The Journal of biological chemistry (ISSN 0021-9258); Volume 275; 39; 30417-22
Publisher Information: United States
Description: In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: CALMODULIN; PLANTS (BOTANY); PROTEINS; ADENOSINE TRIPHOSPHATE; ENZYME ACTIVITY; FLUORESCENCE; MODELS; MUTATIONS; PHOSPHORYLATION
Other Descriptors: CA(2+)-CALMODULIN DEPENDENT PROTEIN KINASE/METABOLISM; CALMODULIN/METABOLISM; PLANT PROTEINS/METABOLISM; RECEPTORS, CALCIUM-SENSING; ADENOSINE TRIPHOSPHATE/METABOLISM; CALCIUM-BINDING PROTEINS/METABOLISM; DANSYL COMPOUNDS; ENZYME ACTIVATION; FLUORESCENCE POLARIZATION; LILIACEAE/ENZYMOLOGY; MODELS, THEORETICAL; MUTATION; NERVE TISSUE PROTEINS/METABOLISM; PHOSPHORYLATION; PROTEIN STRUCTURE, TERTIARY; SEQUENCE DELETION; SUPPORT, U.S. GOV'T, NON-P.H.S; NASA DISCIPLINE PLANT BIOLOGY; NON-NASA CENTER
Availability Source: Other Sources
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