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Kulkarni C, Lo M, Fraseur JG, Tirrell DA, Kinzer-Ursem TL. Bioorthogonal Chemoenzymatic Functionalization of Calmodulin for Bioconjugation Applications. Bioconjug Chem 2015; 26:2153-60. [PMID: 26431265 DOI: 10.1021/acs.bioconjchem.5b00449] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Calmodulin (CaM) is a widely studied Ca(2+)-binding protein that is highly conserved across species and involved in many biological processes, including vesicle release, cell proliferation, and apoptosis. To facilitate biophysical studies of CaM, researchers have tagged and mutated CaM at various sites, enabling its conjugation to fluorophores, microarrays, and other reactive partners. However, previous attempts to add a reactive label to CaM for downstream studies have generally employed nonselective labeling methods or resulted in diminished CaM function. Here we report the first engineered CaM protein that undergoes site-specific and bioorthogonal labeling while retaining wild-type activity levels. By employing a chemoenzymatic labeling approach, we achieved selective and quantitative labeling of the engineered CaM protein with an N-terminal 12-azidododecanoic acid tag; notably, addition of the tag did not interfere with the ability of CaM to bind Ca(2+) or a partner protein. The specificity of our chemoenzymatic labeling approach also allowed for selective conjugation of CaM to reactive partners in bacterial cell lysates, without intermediate purification of the engineered protein. Additionally, we prepared CaM-affinity resins that were highly effective in purifying a representative CaM-binding protein, demonstrating that the engineered CaM remains active even after surface capture. Beyond studies of CaM and CaM-binding proteins, the protein engineering and surface capture methods described here should be translatable to other proteins and other bioconjugation applications.
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Affiliation(s)
- Chethana Kulkarni
- Division of Chemistry and Chemical Engineering, California Institute of Technology , 1200 East California Blvd., Pasadena, California 91125, United States
| | - Megan Lo
- Division of Chemistry and Chemical Engineering, California Institute of Technology , 1200 East California Blvd., Pasadena, California 91125, United States
| | - Julia G Fraseur
- Weldon School of Biomedical Engineering, Purdue University , 206 South Martin Jischke Drive, West Lafayette, Indiana 47907, United States
| | - David A Tirrell
- Division of Chemistry and Chemical Engineering, California Institute of Technology , 1200 East California Blvd., Pasadena, California 91125, United States
| | - Tamara L Kinzer-Ursem
- Division of Chemistry and Chemical Engineering, California Institute of Technology , 1200 East California Blvd., Pasadena, California 91125, United States.,Weldon School of Biomedical Engineering, Purdue University , 206 South Martin Jischke Drive, West Lafayette, Indiana 47907, United States
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Alaimo A, Malo C, Areso P, Aloria K, Millet O, Villarroel A. The use of dansyl-calmodulin to study interactions with channels and other proteins. Methods Mol Biol 2013; 998:217-231. [PMID: 23529433 DOI: 10.1007/978-1-62703-351-0_17] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Steady-state fluorescence spectroscopy is a biophysical technique widely employed to characterize -interactions between proteins in vitro. Only a few proteins naturally fluoresce in cells, but by covalently attaching fluorophores virtually all proteins can be monitored. One of the first extrinsic fluorescent probes to be developed, and that is still in use, is dansyl chloride. We have used this method to monitor the interaction of a variety of proteins, including ion channels, with the Ca(2+)-dependent regulatory protein calmodulin. Here we describe the preparation and use of dansyl-calmodulin (D-CaM).
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Affiliation(s)
- Alessandro Alaimo
- Unidad de Biofísica (CSIC-UPV/EHU), Universidad del País Vasco, Leioa, Spain
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Loving G, Imperiali B. Thiol-reactive derivatives of the solvatochromic 4-N,N-dimethylamino-1,8-naphthalimide fluorophore: a highly sensitive toolset for the detection of biomolecular interactions. Bioconjug Chem 2010; 20:2133-41. [PMID: 19821578 DOI: 10.1021/bc900319z] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The solvatochromic fluorophore 4-N,N-dimethylamino-1,8-naphthalimide (4-DMN) possesses extremely sensitive emission properties due largely to the low intrinsic fluorescence it exhibits in polar protic solvents such as water. This makes it well suited as a probe for the detection of a wide range of biomolecular interactions. Herein we report the development and evaluation of a new series of thiol-reactive agents derived from this fluorophore. The members of this series vary according to linker type and the electrophilic group required for the labeling of proteins and other biologically relevant molecules. Using the calcium-binding protein calmodulin as a model system, we compare the performance of the 4-DMN derivatives to that of several commercially available solvatochromic fluorophores identifying many key factors important to the successful application of such tools. This study also demonstrates the power of this new series of labeling agents by yielding a fluorescent calmodulin construct capable of producing a greater than 100-fold increase in emission intensity upon binding to calcium.
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Affiliation(s)
- Galen Loving
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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Gillespie PG, Cyr JL. Calmodulin binding to recombinant myosin-1c and myosin-1c IQ peptides. BMC BIOCHEMISTRY 2002; 3:31. [PMID: 12453307 PMCID: PMC139967 DOI: 10.1186/1471-2091-3-31] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2002] [Accepted: 11/26/2002] [Indexed: 11/10/2022]
Abstract
BACKGROUND Bullfrog myosin-1c contains three previously recognized calmodulin-binding IQ domains (IQ1, IQ2, and IQ3) in its neck region; we identified a fourth IQ domain (IQ4), located immediately adjacent to IQ3. How calmodulin binds to these IQ domains is the subject of this report. RESULTS In the presence of EGTA, calmodulin bound to synthetic peptides corresponding to IQ1, IQ2, and IQ3 with Kd values of 2-4 microM at normal ionic strength; the interaction with an IQ4 peptide was much weaker. Ca2+ substantially weakened the calmodulin-peptide affinity for all of the IQ peptides except IQ3. To reveal how calmodulin bound to the linearly arranged IQ domains of the myosin-1c neck, we used hydrodynamic measurements to determine the stoichiometry of complexes of calmodulin and myosin-1c. Purified myosin-1c and T701-Myo1c (a myosin-1c fragment with all four IQ domains and the C-terminal tail) each bound 2-3 calmodulin molecules. At a physiologically relevant temperature (25 degrees C) and under low-Ca2+ conditions, T701-Myo1c bound two calmodulins in the absence and three calmodulins in the presence of 5 microM free calmodulin. Ca2+ dissociated nearly all calmodulins from T701-Myo1c at 25 degrees C; one calmodulin was retained if 5 microM free calmodulin was present. CONCLUSIONS We inferred from these data that at 25 degrees C and normal cellular concentrations of calmodulin, calmodulin is bound to IQ1, IQ2, and IQ3 of myosin-1c when Ca2+ is low. The calmodulin bound to one of these IQ domains, probably IQ2, is only weakly associated. Upon Ca2+ elevation, all calmodulin except that bound to IQ3 should dissociate.
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Affiliation(s)
- Peter G Gillespie
- Oregon Hearing Research Center and Vollum Institute, Oregon Health & Science University, Portland OR 97239, USA
| | - Janet L Cyr
- Oregon Hearing Research Center and Vollum Institute, Oregon Health & Science University, Portland OR 97239, USA
- Present address: Department of Otolaryngology & Sensory Neuroscience Research Center, West Virginia University School of Medicine, Morgantown WV 26506, USA
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Popov SG, Krishna UM, Falck JR, Wilkie TM. Ca2+/Calmodulin reverses phosphatidylinositol 3,4, 5-trisphosphate-dependent inhibition of regulators of G protein-signaling GTPase-activating protein activity. J Biol Chem 2000; 275:18962-8. [PMID: 10747990 DOI: 10.1074/jbc.m001128200] [Citation(s) in RCA: 117] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Regulators of G protein signaling (RGS proteins) are GTPase-activating proteins (GAPs) for G(i) and/or G(q) class G protein alpha subunits. RGS GAP activity is inhibited by phosphatidylinositol 3,4,5-trisphosphate (PIP(3)) but not by other lipid phosphoinositides or diacylglycerol. Both the negatively charged head group and long chain fatty acids (C16) are required for binding and inhibition of GAP activity. Amino acid substitutions in helix 5 within the RGS domain of RGS4 reduce binding affinity and inhibition by PIP(3) but do not affect inhibition of GAP activity by palmitoylation. Conversely, the GAP activity of a palmitoylation-resistant mutant RGS4 is inhibited by PIP(3). Calmodulin binds all RGS proteins we tested in a Ca(2+)-dependent manner but does not directly affect GAP activity. Indeed, Ca(2+)/calmodulin binds a complex of RGS4 and a transition state analog of Galpha(i1)-GDP-AlF(4)(-). Ca(2+)/calmodulin reverses PIP(3)-mediated but not palmitoylation-mediated inhibition of GAP activity. Ca(2+)/calmodulin competition with PIP(3) may provide an intracellular mechanism for feedback regulation of Ca(2+) signaling evoked by G protein-coupled agonists.
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Affiliation(s)
- S G Popov
- Pharmacology and Biochemistry Departments, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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Goold R, Baines AJ. Evidence that two non-overlapping high-affinity calmodulin-binding sites are present in the head region of synapsin I. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 224:229-40. [PMID: 8076644 DOI: 10.1111/j.1432-1033.1994.tb20016.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Calmodulin is an important element in the regulation of nerve terminal exocytosis by Ca2+. Calmodulin has been shown to interact with the synaptic vesicle phosphoproteins synapsins Ia and Ib [Okabe, T. & Sobue, K. (1987) FEBS Lett. 213, 184-188; Hayes, N. V. L., Bennett, A. F. & Baines, A. J. (1991) Biochem. J. 275, 93-97]. These proteins are thought to provide regulated linkages between synaptic vesicles and cytoskeletal elements. It is well established that calmodulin modulates synapsin I activities via calmodulin-dependent protein-kinase-II-catalysed phosphorylation. The direct binding of calmodulin to synapsin I suggests a second mode of regulation in addition to phosphorylation. In this study, we present evidence indicating that two sites for calmodulin binding exist in the N-terminal head region of synapsins Ia and Ib. In unphosphorylated synapsin I, these sites had a Kd value of = 36 +/- 14 nM for binding to calmodulin labelled with acetyl-N'-(5-sulpho-1-naphthyl)ethylene diamine. The Kd values for synapsin I phosphorylated at various sites were as follows: site I 18 +/- 11 nM; sites II and III 35 +/- 14 nM; sites I-III 16 +/- 9 nM. The fluorescence data indicated a stoichiometry of not less than 2 mol calmodulin bound to 1 mol synapsin I at saturation in each case. Consistent with this stoichiometry, two chemically cross-linked species (96 kDa and 116 kDa) containing calmodulin and synapsin I were generated in vitro, corresponding to one and two calmodulin molecules bound/synapsin I. Defined fragments of synapsin I were generated with the reagent 2-nitro-5-thiocyanobenzoic acid, which cleaves at cysteine residues. Cysteine-specific cleavage of whole synapsin I after cross-linking to biotinylated calmodulin generated a pair of polypeptide complexes (approximately 46 kDa and 38 kDa), the masses of which indicated cross-linking of calmodulin to the N-terminal and middle regions of synapsin I. Purified N-terminal and middle fragments each showed a Ca(2+)-dependent interaction with calmodulin affinity columns. Two calmodulin-binding fragments (7.4 kDa and 6.5 kDa) were generated using Staphylococcus aureus V8 protease digestion of synapsin I. These fragments were isolated by calmodulin affinity chromatography and reverse-phase HPLC. N-terminal sequence analysis indicated that each was contained within one of the 2-nitro-5-thiocyanobenzoic-acid-derived calmodulin-binding fragments.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- R Goold
- Biological Laboratory, University of Kent, England
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7
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Nakamura F, Mino T, Yamamoto J, Naka M, Tanaka T. Identification of the regulatory site in smooth muscle calponin that is phosphorylated by protein kinase C. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53238-5] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Hanson P, Schulman H. Inhibitory autophosphorylation of multifunctional Ca2+/calmodulin-dependent protein kinase analyzed by site-directed mutagenesis. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)41915-1] [Citation(s) in RCA: 161] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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9
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Correas I, Díaz-Nido J, Avila J. Microtubule-associated protein tau is phosphorylated by protein kinase C on its tubulin binding domain. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)49595-1] [Citation(s) in RCA: 124] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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10
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Ca2(+)-dependent regulation of the spectrin/actin interaction by calmodulin and protein 4.1. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(17)35293-6] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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A calcium-sensitive fluorescent analog of calmodulin based on a novel calmodulin-binding fluorophore. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)30508-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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12
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Bartegi A, Fattoum A, Derancourt J, Kassab R. Characterization of the carboxyl-terminal 10-kDa cyanogen bromide fragment of caldesmon as an actin-calmodulin-binding region. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)77246-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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13
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Tanaka T, Ohta H, Kanda K, Tanaka T, Hidaka H, Sobue K. Phosphorylation of high-Mr caldesmon by protein kinase C modulates the regulatory function of this protein on the interaction between actin and myosin. EUROPEAN JOURNAL OF BIOCHEMISTRY 1990; 188:495-500. [PMID: 2139605 DOI: 10.1111/j.1432-1033.1990.tb15427.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
High-Mr caldesmon, which is involved in smooth muscle contraction, was phosphorylated by protein kinase C. By chymotryptic digestion, actin- and calmodulin-binding assays and immunoprecipitation with the antibody to the C-terminal 35-kDa fragment, we have identified that all phosphate groups are incorporated exclusively into this fragment, which is the functional domain for binding actin and calmodulin. Phosphorylation of high-Mr caldesmon and its C-terminal 35-kDa fragment reduced their binding abilities to both F-actin and calmodulin. Further, their inhibitory effects on the actin-activated ATPase activity of gizzard myosin were also reversed in proportion to the degree of phosphorylation. These results suggest that phosphorylation of high-Mr caldesmon by protein kinase C, which is restricted within the C-terminal 35-kDa domain, results in the modulation of its activity in the smooth muscle actin--myosin interaction.
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Affiliation(s)
- T Tanaka
- Department of Neuropharmacology and Neurochemistry, Osaka University Medical School, Japan
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Harris AS, Croall DE, Morrow JS. Calmodulin Regulates Fodrin Susceptibility to Cleavage by Calciumdependent Protease I. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)71508-1] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Pritchard K, Marston SB. Ca2+-calmodulin binding to caldesmon and the caldesmon-actin-tropomyosin complex. Its role in Ca2+ regulation of the activity of synthetic smooth-muscle thin filaments. Biochem J 1989; 257:839-43. [PMID: 2930490 PMCID: PMC1135664 DOI: 10.1042/bj2570839] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We measured the concentration of calmodulin required to reverse inhibition by caldesmon of actin-activated myosin MgATPase activity, in a model smooth-muscle thin-filament system, reconstituted in vitro from purified vascular smooth-muscle actin, tropomyosin and caldesmon. At 37 degrees C in buffer containing 120 mM-KCl, 4 microM-Ca2+-calmodulin produced a half-maximal reversal of caldesmon inhibition, but more than 300 microM-Ca2+-calmodulin was necessary at 25 degrees C in buffer containing 60 mM-KCl. The binding affinity (K) of caldesmon for Ca2+-calmodulin was measured by a fluorescence-polarization method: K = 2.7 x 10(6) M-1 at 25 degrees C (60 mM-KCl); K = 1.4 x 10(6) M-1 at 37 degrees C in 70 mM-KCl-containing buffer; K = 0.35 x 10(6) M-1 at 37 degrees C in 120 mM-KCl- containing buffer (pH 7.0). At 37 degrees C/120 mM-KCl, but not at 25 degrees C/60 mM-KCl, Ca2+-calmodulin bound to caldesmon bound to actin-tropomyosin (K = 2.9 x 10(6) M-1). Ca2+ regulation in this system does not depend on a simple competition between Ca2+-calmodulin and actin for binding to caldesmon. Under conditions (37 degrees C/120 mM-KCl) where physiologically realistic concentrations of calmodulin can Ca2+-regulate synthetic thin filaments, Ca2+-calmodulin reverses caldesmon inhibition of actomyosin ATPase by forming a non-inhibited complex of Ca2+-calmodulin-caldesmon-(actin-tropomyosin).
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Affiliation(s)
- K Pritchard
- National Heart and Lung Institute, London, U.K
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Cheng A, Fitzgerald TJ, Bhatnagar D, Roskoski R, Carlson GM. Allosteric nucleotide specificity of phosphorylase kinase: correlation of binding, conformational transitions, and activation. Utilization of lin-benzo-ADP to measure the binding of other nucleoside diphosphates, including the phosphorothioates of ADP. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)60597-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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17
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Strasburg GM, Hogan M, Birmachu W, Thomas DD, Louis CF. Site-specific derivatives of wheat germ calmodulin. Interactions with troponin and sarcoplasmic reticulum. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(19)57426-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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18
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19
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Smith CW, Pritchard K, Marston SB. The mechanism of Ca2+ regulation of vascular smooth muscle thin filaments by caldesmon and calmodulin. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(19)75896-7] [Citation(s) in RCA: 97] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Olwin BB, Edelman AM, Krebs EG, Storm DR. Quantitation of energy coupling between Ca2+, calmodulin, skeletal muscle myosin light chain kinase, and kinase substrates. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(18)90605-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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