HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by VanBerkum, M. F. Articles by Means, A. R. Search for Related Content PubMed PubMed Citation Articles by VanBerkum, M. F. Articles by Means, A. R. Social Bookmarking                      What's this?

J. Biol. Chem., Vol. 265, Issue 7, 3750-3756, 03, 1990

Calmodulin activation of target enzymes. Consequences of deletions in the central helix

MF VanBerkum, SE George and AR Means
Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030.

The central helical region of calmodulin (CaM) includes amino acids 65- 92 and serves to separate the two pairs of Ca2(+)-binding sites. This region may impart conformational flexibility and also interact with target proteins. The functional effects of deleting two, three, five, or eight amino acids from the central helix were monitored by examining the activation of phosphodiesterase, smooth muscle myosin light chain (MLC) kinase, and Ca2+/CaM-dependent protein kinase II (CaM kinase II). CaMDM(-8), a calmodulin-deletion mutant with 8 amino acids deleted from the middle of the central helix, failed to activate MLC kinase, phosphodiesterase, or CaM kinase II at physiologically significant concentrations of activator but also had altered electrophoretic mobility and tyrosine fluorescence properties suggesting major changes in the structure of this mutant. Deletion of five amino acids (77-81) resulted in an increase in apparent Kact for phosphodiesterase (150- fold), CaM kinase II (25-fold), and MLC kinase (5-fold) relative to CaM. The maximal autophosphorylation activity of CaM kinase II was also diminished 70% with CaMDM(-5). For phosphodiesterase activation, CaMDM(- 2) has a 15-fold increase in apparent Kact while CaMDM(-3) had an apparent Kact value only 3-fold higher than native CaM. In contrast, the activation of MLC kinase by the two (79-80)- and three (79-81)- amino acid deletion mutants were indistinguishable from each other or native CaM. CaMDM(-2) and CaMDM(-3) stimulated CaM kinase II autophosphorylation to 85 and 70%, respectively, of native CaM with less than a 2-fold increase in Kact. Therefore, all deletions in the central helix of CaM reduce the efficiency of phosphodiesterase activation as reflected by substantial alterations in Kact. MLC kinase activation, however, is relatively insensitive to small two or three amino acid deletions. CaM kinase II interacts with the central helix deletion mutants in a complex manner with alterations in both the Kact and the maximum activity. The data suggest the central helix of CaM may serve as a flexible tether for MLC kinase (and to a lesser extent CaM kinase II) but that an extended conformation of CaM, as predicted from the crystal structure, may be required for phosphodiesterase activation.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				P. Chakrabarty, D. K. Sethi, N. Padhan, K. J. Kaur, D. M. Salunke, S. Bhattacharya, and A. Bhattacharya Identification and Characterization of EhCaBP2: A SECOND MEMBER OF THE CALCIUM-BINDING PROTEIN FAMILY OF THE PROTOZOAN PARASITE ENTAMOEBA HISTOLYTICA J. Biol. Chem., March 26, 2004; 279(13): 12898 - 12908. [Abstract] [Full Text] [PDF]

				J. M. Colomer, M. Terasawa, and A. R. Means Targeted Expression of Calmodulin Increases Ventricular Cardiomyocyte Proliferation and Deoxyribonucleic Acid Synthesis during Mouse Development Endocrinology, March 1, 2004; 145(3): 1356 - 1366. [Abstract] [Full Text] [PDF]

				J. M. Colomer and A. R. Means Chronic Elevation of Calmodulin in the Ventricles of Transgenic Mice Increases the Autonomous Activity of Calmodulin-Dependent Protein Kinase II, Which Regulates Atrial Natriuretic Factor Gene Expression Mol. Endocrinol., August 1, 2000; 14(8): 1125 - 1136. [Abstract] [Full Text]

				E. Kobatake, S. Suzuki, Y. Yanagida, T. Haruyama, and M. Aizawa Genetically Engineered Calmodulin Self-Assembled on Gold Surface Journal of Intelligent Material Systems and Structures, June 1, 1999; 10(6): 446 - 450. [Abstract] [PDF]

				H. Okano, M. S. Cyert, and Y. Ohya Importance of Phenylalanine Residues of Yeast Calmodulin for Target Binding and Activation J. Biol. Chem., October 9, 1998; 273(41): 26375 - 26382. [Abstract] [Full Text] [PDF]

				M. Ikebe, T. Kambara, W. F. Stafford, M. Sata, E. Katayama, and R. Ikebe A Hinge at the Central Helix of the Regulatory Light Chain of Myosin Is Critical for Phosphorylation-dependent Regulation of Smooth Muscle Myosin Motor Activity J. Biol. Chem., July 10, 1998; 273(28): 17702 - 17707. [Abstract] [Full Text] [PDF]

				S. H. Lee, H. Y. Seo, J. C. Kim, W. D. Heo, W. S. Chung, K. J. Lee, M. C. Kim, Y. H. Cheong, J. Y. Choi, C. O. Lim, et al. Differential Activation of NAD Kinase by Plant Calmodulin Isoforms. THE CRITICAL ROLE OF DOMAIN I J. Biol. Chem., April 4, 1997; 272(14): 9252 - 9259. [Abstract] [Full Text] [PDF]

				D. Chin, D. J. Sloan, F. A. Quiocho, and A. R. Means Functional Consequences of Truncating Amino Acid Side Chains Located at a Calmodulin-Peptide Interface J. Biol. Chem., February 28, 1997; 272(9): 5510 - 5513. [Abstract] [Full Text] [PDF]

				A. Persechini, P. M. Stemmer, and I. Ohashi Localization of Unique Functional Determinants in the Calmodulin Lobes to Individual EF Hands J. Biol. Chem., December 13, 1996; 271(50): 32217 - 32225. [Abstract] [Full Text] [PDF]

				D. Chin and A. R. Means Methionine to Glutamine Substitutions in the C-terminal Domain of Calmodulin Impair the Activation of Three Protein Kinases J. Biol. Chem., November 29, 1996; 271(48): 30465 - 30471. [Abstract] [Full Text] [PDF]

				C.-R. Jan, T. J. Ribar, A. R. Means, and G. J. Augustine Alterations in Calcium Channel Currents Underlie Defective Insulin Secretion in a Transgenic Mouse J. Biol. Chem., June 28, 1996; 271(26): 15478 - 15485. [Abstract] [Full Text] [PDF]

				M. Liu, T.-Y. Chen, B. Ahamed, J. Li, and K.-W. Yau Calcium-Calmodulin Modulation of the Olfactory Cyclic Nucleotide-Gated Cation Channel Science, November 25, 1994; 266(5189): 1348 - 1354. [Abstract] [PDF]