Calmodulin

Klee, Claude B.; Vanaman, Thomas C.

doi:10.1016/s0065-3233(08)60470-2

Cited by 882 publications

(468 citation statements)

References 549 publications

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“…The Ca 2 þ -binding protein calmodulin (CaM), which acts as a second messenger in cellular signal transduction pathways and regulates cell proliferation (Klee and Vanaman, 1982;Veigl et al, 1982;Lu and Means, 1993;Schulman, 1993), is one of the molecules involved in the modulation of Ras activity (Agell et al, 2002;Moreto et al, 2008). We have shown that CaM inhibition specifically enhances K-Ras activation provided protein kinase C (PKC) is active.…”

Section: Introductionmentioning

confidence: 88%

K-Ras4B phosphorylation at Ser181 is inhibited by calmodulin and modulates K-Ras activity and function

et al. 2010

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Section: Introductionmentioning

confidence: 88%

K-Ras4B phosphorylation at Ser181 is inhibited by calmodulin and modulates K-Ras activity and function

et al. 2010

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“…Clearly, both the Ca2+ threshold and kinetics will be quite different for mechanisms beginning with pre-bound versus freely diffusing CaM. Because different cell types vary greatly in the fraction of CaM that is pre-bound, and because certain target complexes are known to use CaM as a bound subunit (Klee & Vanaman, 1982;Means, 1988;Luby-Phelps et a1.,'1995), it appears likely that both extremes of activation mechanisms are physiologically important, providing a wide range of thresholds and timecourses for Ca2+/CaM activation. …”

Section: Ob Peersen Et Almentioning

confidence: 99%

“…The affinity of the sk-N11 peptide for Ca2+ loaded CaM was determined by observing peptide Trp fluorescence during direct titration with CaM, resulting in a 0.4 p M KD. In vivo total concentrations of CaM and its target proteins have generally been determined to be in the 1 p M range, although the concentration of freely diffusible CaM is lower (Klee & Vanaman, 1982;Luby-Phelps et al, 1995), and experimental CaM and target concentrations similar to these were used. A CaM concentration of -0.9 p M was used in experiments involving the skMLCK, smMLCK, Ca2+ATPase, and MKII peptides, where the Ca2+ affinities of the complexes were 0.2 p M or less.…”

Section: Culmodulin and Peptidesmentioning

confidence: 99%

Intermolecular tuning of calmodulin by target peptides and proteins: Differential effects on Ca²⁺ binding and implications for kinase activation

1997

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Ca2+-activated calmodulin (CaM) regulates many target enzymes by docking to an amphiphilic target helix of variable sequence. This study compares the equilibrium Ca2+ binding and Ca2+ dissociation kinetics of CaM complexed to target peptides derived from five different CaM-regulated proteins: phosphorylase kinase, CaM-dependent protein kinase 11, skeletal and smooth myosin light chain kinases, and the plasma membrane Ca2+-ATPase. The results reveal that different target peptides can tune the Ca2+ binding affinities and kinetics of the two CaM domains over a wide range of Ca2+ concentrations and time scales. The five peptides increase the Ca2+ affinity of the N-terminal regulatory domain from 14-to 350-fold and slow its Ca2+ dissociation kinetics from 60-to 140-fold. Smaller effects are observed for the C-terminal domain, where peptides increase the apparent Ca2+ affinity 8-to 100-fold and slow dissociation kinetics 13-to 32-fold. In full-length skeletal myosin light chain kinase the inter-molecular tuning provided by the isolated target peptide is further modulated by other tuning interactions, resulting in a CaM-protein complex that has a 10-fold lower Ca2+ affinity than the analogous CaM-peptide complex. Unlike the CaM-peptide complexes, Ca2+ dissociation from the protein complex follows monoexponential kinetics in which all four Ca2+ ions dissociate at a rate comparable to the slow rate observed in the peptide complex. The two Ca2+ ions bound to the CaM N-terminal domain are substantially occluded in the CaM-protein complex. Overall, the results indicate that the cellular activation of myosin light chain kinase is likely to be triggered by the binding of free CaZ2+-CaM or Cq2+-CaM after a Ca2+ signal has begun and that inactivation of the complex is initiated by a single rate-limiting event, which is proposed to be either the direct dissociation of Ca2+ ions from the bound C-terminal domain or the dissociation of Ca2+ loaded C-terminal domain from skMLCK. The observed target-induced variations in Ca2+ affinities and dissociation rates could serve to tune CaM activation and inactivation for different cellular pathways, and also must counterbalance the variable energetic costs of driving the activating conformational change in different target enzymes.Keywords: calcium signaling; calmodulin; kinase regulation; protein-protein interactionsThe ubiquitous protein calmodulin (CaM) plays a crucial role in Ca2+ signaling (Beckingham, 1995;Braun & Schulman, 1995; Clapham, 1995;Wolenski, 1995; Berridge, 1996), where it regulates a wide range of cellular processes by serving as an intracellular receptor for Ca2+ ions (Wheeler et al

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“…Consistent with other theoretical models and available experimental data, the tryptophan residue of melittin at position 19 is shown to be critical to the formation of the complex with the C-terminal domain of peptide enveloped by and protected from oxidation upon binding to the protein. C almodulin is a ubiquitous eukaryotic protein that regulates the activity of a wide variety of enzymes through its binding to them in the presence of calcium [1,2]. The interaction between calmodulin and a target protein is a key step in many calcium-regulated cellular functions [3,4].…”

mentioning

confidence: 99%

“…C almodulin is a ubiquitous eukaryotic protein that regulates the activity of a wide variety of enzymes through its binding to them in the presence of calcium [1,2]. The interaction between calmodulin and a target protein is a key step in many calcium-regulated cellular functions [3,4].…”

mentioning

confidence: 99%

Hydroxyl radical probe of the calmodulin-melittin complex interface by electrospray ionization mass spectrometry

Wong

Maleknia

Downard

2005

J. Am. Soc. Mass Spectrom.

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The calcium-dependent interaction of calmodulin and melittin is studied through the application of a radical probe approach in which solutions of the protein and peptide and protein alone are subjected to high fluxes of hydroxyl and other oxygen radicals on millisecond timescales. These radicals are generated by an electrical discharge within an electrospray ion source of a mass spectrometer. Condensation of the electrosprayed droplets followed by proteolytic digestion of both calmodulin and melittin has identified residues in both which participate in the interaction and/or are shielded from solvent within the protein complex. Consistent with other theoretical models and available experimental data, the tryptophan residue of melittin at position 19 is shown to be critical to the formation of the complex with the C-terminal domain of peptide enveloped by and protected from oxidation upon binding to the protein. C almodulin is a ubiquitous eukaryotic protein that regulates the activity of a wide variety of enzymes through its binding to them in the presence of calcium [1,2]. The interaction between calmodulin and a target protein is a key step in many calcium-regulated cellular functions [3,4]. Calmodulin has also been shown to be able to bind a wide range of smaller ligands, including polypeptides, in which the interaction takes place between amino acid side chains [5,6]. Peptides with little sequence homology, however, are capable of binding to calmodulin, though the majority of peptides that do so have a high propensity to form an amphipathic ␣-helix [7,8] and contain a cluster of basic residues.The interaction between calmodulin and the ␣-helical peptide melittin has been the subject of a number of investigations over the years using a range of spectroscopic approaches [9 -17]. Fluorescence and circular dichroism spectroscopy have revealed that in the presence of calcium, both calmodulin and melittin undergo significant structural changes, particularly in the vicinity of tyrosine residues 99 and 138 in calmodulin and at tryptophan 19 in melittin [9]. Small angle X-ray scattering has also identified significant structural changes in calmodulin with its transformation from a dumbbell to globular conformation upon its binding to melittin [13]. Similar conclusions have been drawn from limited proteolysis experiments followed by mass spectrometric analysis [16].Despite an earlier report on the successful growth of crystals of the calmodulin-melittin complex containing bound calcium [18], no X-ray crystallographic data have been made publicly available. X-ray crystal data for other calmodulin-peptide complexes, however, have been obtained [19] and the structure of the calmodulinmelittin complex predicted [16] based on this data and proton NMR studies for the unbound protein [20]. Nonetheless, to-date there exists no high-resolution experimental data for the calmodulin-melittin complex that represents an important model of calmodulin target recognition.To explore further the interaction between this im-

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Calmodulin

Cited by 882 publications

References 549 publications

K-Ras4B phosphorylation at Ser181 is inhibited by calmodulin and modulates K-Ras activity and function

K-Ras4B phosphorylation at Ser181 is inhibited by calmodulin and modulates K-Ras activity and function

Intermolecular tuning of calmodulin by target peptides and proteins: Differential effects on Ca²⁺ binding and implications for kinase activation

Hydroxyl radical probe of the calmodulin-melittin complex interface by electrospray ionization mass spectrometry

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Calmodulin

Cited by 882 publications

References 549 publications

K-Ras4B phosphorylation at Ser181 is inhibited by calmodulin and modulates K-Ras activity and function

K-Ras4B phosphorylation at Ser181 is inhibited by calmodulin and modulates K-Ras activity and function

Intermolecular tuning of calmodulin by target peptides and proteins: Differential effects on Ca2+ binding and implications for kinase activation

Hydroxyl radical probe of the calmodulin-melittin complex interface by electrospray ionization mass spectrometry

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Intermolecular tuning of calmodulin by target peptides and proteins: Differential effects on Ca²⁺ binding and implications for kinase activation