Troponin I Inhibitory Peptide (96−115) Has an Extended Conformation When Bound to Skeletal Muscle Troponin C†

Biochemistry ◽  
1999 ◽  
Vol 38 (21) ◽  
pp. 6911-6917 ◽  
Author(s):  
Griselda Hernández ◽  
Donald K. Blumenthal ◽  
Michael A. Kennedy ◽  
Clifford J. Unkefer ◽  
Jill Trewhella
Keyword(s):  
Skeletal Muscle ◽  
Troponin I ◽  
Troponin C ◽  
Inhibitory Peptide ◽  
Extended Conformation

Ca2+, Mg2+, and Troponin I Inhibitory Peptide Binding to a Phe-154 to Trp Mutant of Chicken Skeletal Muscle Troponin C

Biochemistry ◽  
1994 ◽  
Vol 33 (10) ◽  
pp. 2961-2969 ◽  
Author(s):  
Murali Chandra ◽  
William D. McCubbin ◽  
Kim Oikawa ◽  
Cyril M. Kay ◽  
Lawrence B. Smillie
Keyword(s):  
Skeletal Muscle ◽  
Troponin I ◽  
Peptide Binding ◽  
Troponin C ◽  
Inhibitory Peptide ◽  
Trp Mutant ◽  
Chicken Skeletal Muscle

Calmodulin and troponin C: affinity chromatographic study of divalent cation requirements for troponin I inhibitory peptide (residues 104–115), mastoparan, and fluphenazine binding

1987 ◽  
Vol 65 (11) ◽  
pp. 982-988 ◽  
Author(s):  
Jennifer E. Van Eyk ◽  
Robert S. Hodges
Keyword(s):  
Troponin I ◽  
Troponin C ◽  
Homologous Region ◽  
Affinity Column ◽  
Chromatographic Study ◽  
Inhibitory Peptide ◽  
Receptor Sites ◽  
Inhibitory Region ◽  
Correct Alignment ◽  
Correct Structure

The different conformations induced by the binding of Mg2+ or Ca2+ to troponin C (TnC) and calmodulin (CaM) results in the exposure of various interfaces with potential to bind target compounds. The interaction of TnC or CaM with three affinity columns with ligands of either the synthetic peptide of troponin I (TnI) inhibitory region (residues 104–115), mastoparan (a wasp venom peptide), or fluphenazine (a phenothiazine drug) were investigated in the presence of Mg2+ or Ca2+. TnC and CaM in the presence of either Ca2+ or Mg2+ bound to the TnI peptide 104–115. The cation specificity for this interaction firmly establishes that the TnI inhibitory region binds to the high affinity sites of TnC (most likely the N-terminal helix of site III) and presumably the homologous region of CaM. Mastoparan interacted strongly with both proteins in the presence of Ca2+ but, in the presence of Mg2+, did not bind to TnC and only bound weakly to CaM. Fluphenazine bound to TnC and CaM only in the presence of Ca2+. When the ligands interacted with either proteins there was an increase in cation affinity, such that TnC and CaM were eluted from the TnI peptide or mastoparan affinity column with 0.1 M EDTA compared with the 0.01 M EDTA required to elute the proteins from the fluphenazine column. The interaction of these ligands with their receptor sites on TnC and CaM require a specific and spatially correct alignment of hydrophobic and negatively charged residues on these proteins. In the case of the TnI peptide, which represents a naturally occurring target protein for TnC, Mg2+ and Ca2+ can induce the correct structure in TnC or CaM for interaction, while only Ca2+ can induce the correct structure for mastoparan or fluophenazine binding.

Cardiac troponin I inhibitory peptide: location of interaction sites on troponin C

FEBS Letters ◽  
2000 ◽  
Vol 469 (2-3) ◽  
pp. 168-172 ◽  
Author(s):  
M.Bret Abbott ◽  
Alex Dvoretsky ◽  
Vadim Gaponenko ◽  
Paul R Rosevear
Keyword(s):  
Cardiac Troponin ◽  
Troponin I ◽  
Troponin C ◽  
Cardiac Troponin I ◽  
Inhibitory Peptide ◽  
Interaction Sites

scholarly journals Calcium ion-regulated thin filaments from vascular smooth muscle

1980 ◽  
Vol 185 (2) ◽  
pp. 355-365 ◽  
Author(s):  
S B Marston ◽  
R M Trevett ◽  
M Walters
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Atpase Activity ◽  
Thin Filament ◽  
Troponin I ◽  
Troponin C ◽  
Myosin Atpase ◽  
Protein G ◽  
Thin Filaments ◽  
Myosin Atpase Activity

Myosin and actin competition tests indicated the presence of both thin-filament and myosin-linked Ca2+-regulatory systems in pig aorta and turkey gizzard smooth-muscle actomyosin. A thin-filament preparation was obtained from pig aortas. The thin filaments had no significant ATPase activity [1.1 +/- 2.6 nmol/mg per min (mean +/- S.D.)], but they activated skeletal-muscle myosin ATPase up to 25-fold [500 nmol/mg of myosin per min (mean +/- S.D.)] in the presence of 10(-4) M free Ca2+. At 10(-8) M-Ca2+ the thin filaments activated myosin ATPase activity only one-third as much. Thin-filament activation of myosin ATPase activity increased markedly in the range 10(-6)-10(-5) M-Ca2+ and was half maximal at 2.7 × 10(-6) M (pCa2+ 5.6). The skeletal myosin-aorta-thin-filament mixture gave a biphasic ATPase-rate-versus-ATP-concentration curve at 10(-8) M-Ca2+ similar to the curve obtained with skeletal-muscle thin filaments. Thin filaments bound up to 9.5 mumol of Ca2+/g in the presence of MgATP2-. In the range 0.06-27 microM-Ca2+ binding was hyperbolic with an estimated binding constant of (0.56 +/- 0.07) x 10(6) M-1 (mean +/- S.D.) and maximum binding of 8.0 +/- 0.8 mumol/g (mean +/- S.D.). Significantly less Ca2+ bound in the absence of ATP. The thin filaments contained actin, tropomyosin and several other unidentified proteins. 6 M-Urea/polyacrylamide-gel electrophoresis at pH 8.3 showed proteins that behaved like troponin I and troponin C. This was confirmed by forming interspecific complexes between radioactive skeletal-muscle troponin I and troponin C and the aorta thin-filament proteins. The thin filaments contained at least 1.4 mumol of a troponin C-like protein/g and at least 1.1 mumol of a troponin I-like protein/g.

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