ライフサイエンスコーパス: cTnC

1 cTnC contains two EF-hand domains (the N and C domain of

2 findings from this study were as follows: 1) cTnC mutants demonstrated distinct functional phenotypes

3 omplexes containing sTnC (26 +/- 0.1 s(-1)), cTnC (38 +/- 0.9 s(-1)) and xsTnC (50 +/- 1.2 s(-1)) cor

4 intermediate between 100% cTnC-A31S and 100% cTnC-WT, whereas the mutant increased the activation of

5 nsitivity that was intermediate between 100% cTnC-A31S and 100% cTnC-WT, whereas the mutant increased

6 d Ca2+ sensitivity, whereas the cTnI-(1-151).cTnC complex did not restore any Ca2+ sensitivity.

7 We found that the cTnI-(1-188).cTnC complex only partially restored Ca2+ sensitivity, w

8 In contrast to apo- and 3Ca(2+)-cTnC, the drug-bound complex displays a fully open N-ter

9 proteins which retain the endogenous Cys 35 (cTnC(C35)) or Cys 84 (cTnC(C84)) would provide fluoresce

10 nC(C84), near the D/E helix linker); Cys-35 (cTnC(C35), at nonfunctional site I); or near the C-termi

11 omyosin ATPase assays with 50% cTnC-A31S:50% cTnC-WT demonstrated Ca(2+) sensitivity that was interme

12 onstituted actomyosin ATPase assays with 50% cTnC-A31S:50% cTnC-WT demonstrated Ca(2+) sensitivity th

13 the endogenous Cys 35 (cTnC(C35)) or Cys 84 (cTnC(C84)) would provide fluorescent probes with distinc

14 cysteine mutants allowed labeling at Cys-84 (cTnC(C84), near the D/E helix linker); Cys-35 (cTnC(C35)

15 erminus with a cysteine inserted at site 98 (cTnC-C35S,C84S,S98C, cTnC(C98)).

16 orted mechanism for the binding of Ca2+ to a cTnC mutant labeled with the same probe at Cys-84.

17 filament regulation is modulated by altered cTnC-cTnI interactions due to charge modification caused

18 lecular interactions between TnI helix 4 and cTnC helix A, specifically revealing a new, to our knowl

19 With 5'ATR-labeled cTnC(C84) and cTnC(C98) dichroism increased with increasing [Ca2+], wh

20 on relationships when comparing the cTnC and cTnC:CBMII TnC fibres.

21 , we probed the interaction between cTnI and cTnC fragments, cTnC1-89 and cTnC90-162 (recombinant pep

22 d phosphorylation signaling between cTnI and cTnC.

23 lated) in the presence of wild-type cTnI and cTnC.

24 When cTnT, cTnI, and cTnC were incubated individually with caspase-3, there w

25 to the N-terminal lobes of 4Ca(2+)-sTnC and cTnC bound to a C-terminal fragment of cardiac troponin

26 ed cardiomyopathy linked cTnC Gly159 to Asp (cTnC-G159D) mutation on the development of Ca(2+)-depend

27 +) binding causes structural changes between cTnC and two critical regions of cardiac muscle troponin

28 y shortening the intersite distances between cTnC and cTnI.

29 e inhibitory region in the interface between cTnC and cTnI in holo cardiac troponin.

30 and calculated interaction strengths between cTnC and each of Ca(2+) and TnISW Surprisingly the Ca(2+

31 )-saturated) states in reconstituted binary (cTnC-cTnI) and ternary (cTnC-cTnI-cTnT) troponin complex

32 (236-285), cTnI-R145G/S23D/S24D Ca(2+)-bound cTnC(1-161)-cTnI(1-172)-cTnT(236-285), and cTnI-R145G/PS

33 amics simulations of cTnI-R145G Ca(2+)-bound cTnC(1-161)-cTnI(1-172)-cTnT(236-285), cTnI-R145G/S23D/S

34 -285), and cTnI-R145G/PS23/PS24 Ca(2+)-bound cTnC(1-161)-cTnI(1-172)-cTnT(236-285), respectively.

35 ts determined for free and cTnI(33-80)-bound cTnC(81-161).

36 on, with the probe orientation of Ca2+-bound cTnC significantly affected by Ca2+ binding at neighbori

37 f the N-terminal domain of cTnC, followed by cTnC binding the troponin I switch peptide (TnISW).

38 diomyopathy mutations in cardiac troponin C (cTnC) (A8V, C84Y, E134D, and D145E) were reported, and t

39 eract with the N lobe of cardiac troponin C (cTnC) and that phosphorylation at Ser(23/24) weakens the

40 on between IAANS-labeled cardiac troponin C (cTnC) and the two cTnI mutants.

41 racts with the N-lobe of cardiac troponin C (cTnC) and thus is positioned to modulate myofilament Ca2

42 tations in TNNC1-encoded cardiac troponin C (cTnC) are a relatively rare cause of HCM.

43 ociated mutant D145E, in cardiac troponin C (cTnC) C-domain, causes generalised instability at multip

44 he solution structure of cardiac troponin C (cTnC) challenges existing structure/function models for

45 the C-terminal domain of cardiac troponin C (cTnC) comprising residues 81-161.

46 T cardiac troponin T/I + cardiac troponin C (cTnC) D65A (a site II inactive cTnC mutant).

47 cer-promoter of the slow/cardiac troponin C (cTnC) gene contains five protein binding regions, four o

48 Troponin C (cTnC) interaction with cTnI (C-I interaction) is a criti

49 Cardiac troponin C (cTnC) is the Ca(2+)-binding component of the troponin co

50 Cardiac troponin C (cTnC) is the calcium-dependent switch for contraction in

51 Cardiac troponin C (cTnC) is the regulatory protein that initiates cardiac c

52 , using a monocysteine mutant of troponin C (cTnC) labeled with the fluorescent probe 2-[(4'-(iodoace

53 clude the opening of the cardiac troponin C (cTnC) N-domain, the change of secondary structure of the

54 nal domain in Ca2+-bound cardiac troponin C (cTnC) presents a much different binding surface for Ca2+

55 l regulatory lobe of the cardiac troponin C (cTnC) subunit in the troponin complex.

56 rminal region that binds cardiac troponin C (cTnC) to increase the calcium sensitivity of the sarcome

57 he cardiac-specific slow/cardiac troponin C (cTnC) transcriptional enhancer and overexpression of GAT

58 hodamine (5'ATR)-labeled cardiac troponin C (cTnC) was measured to monitor cTnC structure during Ca2+

59 initiated by binding of Ca2+ to troponin C (cTnC) which induces a series of structural changes in cT

60 tiated by Ca2+ dissociation from troponin C (cTnC), followed by multiple structural changes of thin f

61 sensor of the sarcomere, cardiac troponin C (cTnC), plays an important role in regulating muscle cont

62 TNNC1, which encodes cardiac troponin C (cTnC), remains elusive as a dilated cardiomyopathy (DCM)

63 egulatory site of cardiac muscle troponin C (cTnC).

64 are reported to bind to cardiac troponin C (cTnC).

65 minal regulatory site of cardiac troponin C (cTnC).

66 ding properties between the teleost cardiac (cTnC or TnC1a) and slow-skeletal (ssTnC or TnC1b) paralo

67 1) three of the hypertrophic cardiomyopathy cTnC mutants increased the Ca(2+) sensitivity of the myo

68 g with a single lobe of a somewhat compacted cTnC that sits at one end of an elongated rodlike cTnI,

69 d enhanced cross-bridge cycling in controls, cTnC-G159D specifically blunted the phosphorylation indu

70 cTnI-R145G mutation on the dynamics of cTn, cTnC Ca(2+) handling, and the C-I interaction.

71 onstituted with a mono-cysteine mutant cTnC (cTnC(C84)), dichroism of the 5'ATR probe attached to Cys

72 A (cTnI + cTnC in Mg2+), and 51.6 A (cTnI + cTnC in Mg2+ + Ca2+).

73 alone), 48.3 A (cTnI + cTnC), 46.3 A (cTnI + cTnC in Mg2+), and 51.6 A (cTnI + cTnC in Mg2+ + Ca2+).

74 mutant: 44.4 A (cTnI alone), 48.3 A (cTnI + cTnC), 46.3 A (cTnI + cTnC in Mg2+), and 51.6 A (cTnI +

75 we monitored Ca(2+)-induced changes in cTnI-cTnC interactions.

76 of the antiparallel organization of the cTnI-cTnC complex, it is not clear how the phosphorylation si

77 as released from site II of cTnC in the cTnI.cTnC complex (122/s) was 12.5-fold faster than for the s

78 Addition of cTnT3 to the cTnI.cTnC complex resulted in a 3.6-fold decrease in the Ca(2

79 ts was tested in myofibrils, from which cTnI.cTnC was extracted by exchanging endogenous cardiac trop

80 tion of cTnI with cardiac troponin T (cTnT), cTnC, or cTnC and cTnT in the absence of bound regulator

81 ng information resulting from the deuterated cTnC subunit, the unlabeled cTnI-cTnT(198-298) subunits,

82 values of [Ca2+] and compared with different cTnC:CBMII TnC ratios at a saturating [Ca2+].

83 PyMol modeling of each cTnC mutant within the cTn complex revealed potential fo

84 rease in k(tr) was greatly reduced following cTnC or xsTnC reconstitution because k(tr) at low levels

85 nity for actin and a heightened affinity for cTnC.

86 These characteristics are not seen for cTnC(C84).

87 r of magnitude smaller for troponin than for cTnC.

88 M-1 s-1, a factor of 3 smaller than that for cTnC.

89 valently bound to a small percentage of free cTnC after prolonged incubation with the protein.

90 pecifically to the C-terminal domain of free cTnC.

91 demonstrate binding of levosimendan to free cTnC, and the presence of levosimendan had no apparent e

92 n induced by release of regulatory Ca2+ from cTnC occurs in one step (t1/2 approximately 5 ms), and t

93 iation of the regulatory region of cTnI from cTnC.

94 Corresponding data from cTnC(C98) reconstituted trabeculae were 5.53 (+/-0.03) a

95 id not affect Ca(2+) dissociation rates from cTnC at pH 7.0 or 6.5.

96 n involve Ca(2+) binding to and release from cTnC (troponin C) and structural changes in cTnC and oth

97 ophic cardiomyopathy-cardiac troponin C (HCM-cTnC) mutants.

98 that incorporation of the A8V and D145E HCM-cTnC mutants, but not E134D into thin filaments (TFs), i

99 entiate the Ca(2+)-sensitizing effect of HCM-cTnC mutants on the myofilament.

100 Single mutations L29Q and G159D in human cTnC have been reported to associate with familial hyper

101 of cTnI, the D-E linker of cTnC, and site II cTnC.

102 in the absence of bound regulatory Ca(2+) in cTnC.

103 cTnC (troponin C) and structural changes in cTnC and other thin filament proteins triggered by Ca(2+

104 ch induces a series of structural changes in cTnC and other thin filament proteins.

105 f active cycling cross-bridges to changes in cTnC structure was determined by inhibition of force to

106 th force and activation-dependent changes in cTnC structure were influenced by SL.

107 and 1.02 (+/-0.09) (n = 5) for dichroism in cTnC(C84) reconstituted trabeculae.

108 activation, k(tr) was similarly elevated in cTnC-reconstituted fibres with ATP or when cross-bridge

109 e and the N terminus of the central helix in cTnC.

110 hy-causing mutations have been identified in cTnC, the limited information about their structural def

111 bind Ca(2+) as a result of modifications in cTnC structure.

112 but this effect was considerably reduced in cTnC reconstituted fibres, and eliminated in xsTnC recon

113 HCM, RCM, and DCM mutations; 2) a region in cTnC associated with increased Ca(2+) sensitivity in ski

114 erminal methionine methyl chemical shifts in cTnC upon association with cTnI suggest that cTnI associ

115 This subregion in cTnC makes a likely target against which to design new a

116 c troponin C (cTnC) D65A (a site II inactive cTnC mutant).

117 s in the N- and C-terminal domains of intact cTnC that exhibit fast exchange on the NMR time scale.

118 ene-6-sulfonic acid fluorescence in isolated cTnC or the cTn complex.

119 trated increased Ca(2+) affinity in isolated cTnC, the troponin complex, thin filament, and to a less

120 mutations on the Ca(2+) affinity of isolated cTnC, cTn, and TF are not sufficient to explain the larg

121 in relative to the Ca2+ affinity of isolated cTnC.

122 different metal-bound states of the isolated cTnCs showed changes in the secondary structure of A8V,

123 The dichroism of 5'ATR-labeled cTnC(C35) was insensitive to either Ca2+ or strong cross

124 With 5'ATR-labeled cTnC(C84) and cTnC(C98) dichroism increased with increas

125 ichroism to increase more with 5'ATR-labeled cTnC(C84) than cTnC(C98).

126 With 5'ATR-labeled cTnC(C84) Vi caused both the pCa50)of dichroism and the

127 Ca 4.0 to decrease, while with 5'ATR-labeled cTnC(C98) the pCa50 of dichroism decreased with no chang

128 The doubly labeled cTnC mutant was reconstituted into the thin filament by

129 een cardiac troponin I and the IAANS-labeled cTnC mutant were very similar to those obtained from rec

130 inity of site II for Ca2+ when IAANS-labeled cTnC(C35) is bound to cTnI.

131 the pCa50 of fluorescence for IAANS-labeled cTnC(C84), but induced a rightward shift in the pCa50 of

132 uorescence were coincident for IAANS-labeled cTnC(C84).

133 coherence spectra of [methyl-13C]Met-labeled cTnC indicate that bepridil and trifluoperazine bind to

134 binding to [methyl-(13)C]methionine-labeled cTnC when free or when complexed with cardiac troponin I

135 In contrast to the case with full-length cTnC, neither cTnC1-89 nor cTnC90-162 induced significan

136 effect of the dilated cardiomyopathy linked cTnC Gly159 to Asp (cTnC-G159D) mutation on the developm

137 may represent a mechanism to modulate C-lobe cTnC interactions with the N domain of cTnI.

138 ution structure of the Mg(2+)-loaded C lobe, cTnC(81-161), in a complex with the N domain of cardiac

139 ac troponin C (cTnC) was measured to monitor cTnC structure during Ca2+-activation of force in rat sk

140 ation, we replaced native cTnC with a mutant cTnC (DM-TnC) that is incapable of binding Ca(2+).

141 ae reconstituted with a mono-cysteine mutant cTnC (cTnC(C84)), dichroism of the 5'ATR probe attached

142 to one cysteine of a double-cysteine mutant cTnC(13C/51C) as a FRET donor and attaching DDPM to the

143 ceptor (DDPM)-labeled double-cysteine mutant cTnC(T13C/N51C)AEDANS-DDPM was incorporated into skinned

144 l studies using the recombinant human mutant cTnC proteins reconstituted into porcine papillary skinn

145 vidence of an allosteric mechanism in mutant cTnC that may play a role to the HCM phenotype.

146 M) attached the other cysteine of the mutant cTnC(L13C/N51C).

147 Circular dichroism of mutant cTnCs revealed a trend where increased alpha-helical con

148 The double mutant, cTnC(L12W/N51C) labeled with 1,5-IAEDANS at Cys-51, serv

149 The interaction between N-cTnC and cTnI stabilizes the Ca(2+)-induced opening of N

150 ation, the N-domain of cardiac troponin C (N-cTnC) binds to Ca(2+) and interacts with the actomyosin

151 ated into skinned muscle fibers to monitor N-cTnC opening.

152 f sarcomere length on N-cTnC, we monitored N-cTnC opening at relaxing and saturating levels of Ca(2+)

153 I stabilizes the Ca(2+)-induced opening of N-cTnC and is presumed to also destabilize cTnI-actin inte

154 a(2+)-dependent conformational behavior of N-cTnC in skinned cardiac muscle fibers.

155 blunted the effect of sarcomere length on N-cTnC conformational behavior such that weak-binding cros

156 effect of strongly bound cross-bridges on N-cTnC opening (which we interpret as transmitted through

157 eak-binding cross-bridges had no effect on N-cTnC opening at any tested [Ca(2+)] or sarcomere length.

158 tu steady-state FRET measurements based on N-cTnC opening suggested that at long sarcomere length, st

159 structural effects of sarcomere length on N-cTnC, we monitored N-cTnC opening at relaxing and satura

160 directly stabilize this Ca(2+)-sensitizing N-cTnC-cTnI interaction through structural effects on trop

161 ously used was unable to determine whether N-cTnC opening depends on sarcomere length.

162 u into skinned cardiac muscle fibers, native cTnC with IAANS bound to both Cys 35 and Cys 84 showed a

163 a50 of fluorescence for IAANS-labeled native cTnC.

164 Although progressive replacement of native cTnC with DM-TnC caused an expected monotonic decrease i

165 thin-filament activation, we replaced native cTnC with a mutant cTnC (DM-TnC) that is incapable of bi

166 bridge between His-164 of cTnI and Glu-19 of cTnC.

167 ring the distance changes from residue 89 of cTnC to residues 151 and 167 of cTnI, respectively.

168 ent effect on the Ca(2+) binding affinity of cTnC.

169 reduction in interactions between helix C of cTnC (residues 56, 59, and 63), and cTnI (residue 145) i

170 Free energy perturbation calculation of cTnC Ca(2+) binding for these conformations showed relat

171 enhancer-promoter binding protein complex of cTnC augments DNA bending and facilitates the DNA bindin

172 the conformational change of the N-domain of cTnC and the dissociation of the regulatory region of cT

173 ening of the N-terminal regulatory domain of cTnC as measured using Forster resonance energy transfer

174 Ca(2+) affinity of the N-terminal domain of cTnC in isolation is insufficient to explain the pathoge

175 bic patch of the open regulatory N-domain of cTnC pulls the inhibitory region away from actin upon Ca

176 al transitions in the regulatory N-domain of cTnC that are involved in either activation (L29Q) or de

177 al transitions in the regulatory N-domain of cTnC triggered by Ca(2+) binding and dissociation.

178 targets, possibly including the N-domain of cTnC when it is in its open Ca(2+)-saturated state.

179 tension to the open state of the N-domain of cTnC with variations in the state of cTnI, we were able

180 s two EF-hand domains (the N and C domain of cTnC, cNTnC and cCTnC) connected by a flexible linker.

181 with the opening of the N-terminal domain of cTnC, followed by cTnC binding the troponin I switch pep

182 coupled to the open state of the N-domain of cTnC.

183 dissociation of the RR from the N-domain of cTnC.

184 des corresponding to the N- and C-domains of cTnC).

185 c interaction between R171of cTnI and E15 of cTnC, which structurally phenocopied the ssTnI conformat

186 propose that the preferential expression of cTnC at lower temperatures increases myofilament Ca(2+)

187 Moreover, neither fragment of cTnC could significantly restore Ca2+ regulation of forc

188 Mutationally induced changes at site II of cTnC alter calcium coordination that corresponds to biop

189 at which Ca(2+) was released from site II of cTnC in the cTnI.cTnC complex (122/s) was 12.5-fold fast

190 at which Ca(2+) dissociated from site II of cTnC in Tn complexes also depended on the cTnT isoform p

191 ne substitutions (italics) within site II of cTnC to investigate whether these residues are essential

192 and dynamic changes from TNT1 to site II of cTnC, including TNT1, cTnT linker, I-T arm, regulatory d

193 ons propagate to the cTn core and site II of cTnC, where calcium binding and dissociation occurs.

194 y associated with Ca2+ binding to site II of cTnC, whereas the slow component may arise from cross-br

195 the Ca(2+) dissociation rate from site II of cTnC.

196 the Ca(2+) dissociation rate from site II of cTnC.

197 regulatory domain of cTnI, the D-E linker of cTnC, and site II cTnC.

198 in weakening interactions with the N-lobe of cTnC and a re-positioning of the acidic amino terminus o

199 utation is located in the C-terminal lobe of cTnC, the G159D mutation was demonstrated to depress ATP

200 The regulatory N-terminal lobe of cTnC, unlike that of skeletal troponin C (sTnC), contain

201 ition in the cardiac regulatory or N lobe of cTnC.

202 sion (CPMG-RD), and affinity measurements of cTnC for the thin filament in reconstituted papillary mu

203 th either cardiac TnC (cTnC) or a mixture of cTnC and an inactive mutant cardiac TnC (CBMII TnC).

204 ut with a double mutant or triple mutants of cTnC, reconstituted into troponin with tryptophanless cT

205 ious results showed that the closing rate of cTnC N-domain triggered by Ca(2+) dissociation was subst

206 The cardiac-specific enhancer region of cTnC contains at least one possible HMG binding region a

207 , which interacts with C-terminal regions of cTnC and cTnT, is of particular significance in transduc

208 saturation of the Ca(2+) regulatory site of cTnC in the complexes.

209 n signal from cTnI to the regulatory site of cTnC involves a global change in cTnI structure.

210 r from the regulatory Ca(2+)-binding site of cTnC.

211 -bridges perturb the N-terminal structure of cTnC at Cys-84, while C-terminal structure is altered by

212 While the tertiary structure of cTnC(81-161) is qualitatively similar to that observed f

213 We have determined the crystal structure of cTnC, with three bound Ca(2+) ions, complexed with the c

214 ng sites for trifluoperazine and bepridil on cTnC.

215 ubstitution had no effect on Ca2+ binding on cTnC in solution.

216 in but showed no global structural effect on cTnC opening.

217 TnI with cardiac troponin T (cTnT), cTnC, or cTnC and cTnT in the absence of bound regulatory Ca(2+)

218 he current study was to generate recombinant cTnC proteins with single Cys residues as sites for atta

219 he cTn complex structure (including residues cTnC 1-161, cTnI 1-172, and cTnT 236-285) with the N-ter

220 ne inserted at site 98 (cTnC-C35S,C84S,S98C, cTnC(C98)).

221 and side-chain resonances of Ca2+-saturated cTnC(81-161) both free and bound to cTnI(33-80).

222 rmined solution structures of Ca2+-saturated cTnC(81-161) free and bound to cTnI(33-80).

223 2/s) was 12.5-fold faster than for the ssTnI.cTnC complex (9.8/s).

224 Addition of cTnT3 to the ssTnI.cTnC complex resulted in a 1.9-fold increase in the Ca(2

225 binding of cTnI(33-80), onto the C-terminal cTnC structure.

226 econstituted binary (cTnC-cTnI) and ternary (cTnC-cTnI-cTnT) troponin complexes.

227 d that ssTnC has higher Ca(2+) affinity than cTnC for Ca(2+) overall, whereas each of the paralogs ha

228 rease more with 5'ATR-labeled cTnC(C84) than cTnC(C98).

229 We anticipated that cTnC proteins which retain the endogenous Cys 35 (cTnC(C

230 erimental results and modeling indicate that cTnC adopts a partially collapsed conformation, while th

231 ese data can be interpreted to indicate that cTnC with IAANS bound to both Cys 35 and C84 senses eith

232 ntire contrast variation series suggest that cTnC and the cTnI-cTnT(198-298) component lie with their

233 The cTnC N-domain conformational change was examined by moni

234 The cTnC-cTnI interaction was investigated by monitoring the

235 phosphorylation and this mutation alter the cTnC-cTnI (C-I) interaction, which plays a crucial role

236 relationship between the cTnC fibres and the cTnC:CBMII TnC fibres would be apparent.

237 he velocity-tension relationship between the cTnC fibres and the cTnC:CBMII TnC fibres would be appar

238 ity-tension relationships when comparing the cTnC and cTnC:CBMII TnC fibres.

239 ically the closing of the cTnC N-domain, the cTnC-cTnI (troponin I) interaction, and the cTnI-actin i

240 ics of Ca(2+) dissociation (k(off)) from the cTnC mutants in the presence of TFs and S1.

241 5 ms) correlated with Ca2+ release from the cTnC N-domain.

242 Furthermore, the cTnC mutants diminished (Y5H and I148V) or abolished (M1

243 separation between these two proteins in the cTnC-cTnI interface.

244 ural change was significantly reduced in the cTnC-cTnI(43E/45E/144E/146G) complex.

245 of the divalent cation-binding sites of the cTnC C-domain.

246 The affinities of the cTnC for the truncated cTnI mutant were: (1) 1.5 x 10(6)

247 uld result in increased transcription of the cTnC gene during the proliferation phase of embryonic ca

248 onstrate that the structural dynamics of the cTnC molecule are key in determining myofilament Ca(2+)

249 The secondary structure of the cTnC mutant was evaluated by circular dichroism, which d

250 g(2+)-bound states indicated that all of the cTnC mutants (except I148V in the Ca(2+)/Mg(2+) conditio

251 3) changes in the secondary structure of the cTnC mutants may contribute to modified protein-protein

252 kinetics of the structural transition of the cTnC N-domain but showed no global structural effect on

253 red to achieve a fully open structure of the cTnC N-domain in regulated thin filaments.

254 The closing of the cTnC N-domain induced by release of regulatory Ca2+ from

255 n filaments, specifically the closing of the cTnC N-domain, the cTnC-cTnI (troponin I) interaction, a

256 kinetics of the structural transition of the cTnC N-domain.

257 of cTnI on the conformational changes of the cTnC N-domain.

258 vide novel evidence that modification of the cTnC-cTnI interaction has distinct effects on troponin C

259 We have investigated the structure of the cTnC-cTnI-cTnT(198-298) calcium-saturated, ternary cardi

260 The unloaded shortening velocity of the cTnC-replaced fibres was determined at various values of

261 fferent isotopically labeled variants of the cTnC/cTnI/cTnT(198-298) complex, one of which contained

262 Therefore, it appears that the cTnC Ca(2+) off-rate is most likely to be affected rathe

263 mescale simulations have calculated that the cTnC paralog transitions from the closed to the open sta

264 tive ternary complexes and the fact that the cTnC subunit is not highly intertwined with the other su

265 Our results demonstrate that the cTnC-G159D mutation by itself does not alter the myofila

266 w evidence of binding of levosimendan to the cTnC.cTnI complex.

267 overexpression of GATA-5 transactivates the cTnC enhancer in noncardiac muscle cell lines.

268 wn to decrease KCa and pCa50, and weaken the cTnC-cTnI (C-I) interaction.

269 c skinned fibers were reconstituted with the cTnC-A31S mutant, which increased Ca(2+) sensitivity wit

270 ends sharply at the end interacting with the cTnC/cTnT(198-298) component, which reorients so as to m

271 This open conformation within the cTnC.cTnI complex has properties favorable for the Ca(2+

272 nts in purified troponin confirmed that this cTnC-G159D blunting of myofilament desensitization resul

273 ces in the N-terminal domain of cardiac TnC (cTnC) by fluorescence resonance energy transfer measurem

274 racted and replaced with either cardiac TnC (cTnC) or a mixture of cTnC and an inactive mutant cardia

275 ed by replacing native TnC with cardiac TnC (cTnC) or a site I-inactive skeletal TnC mutant (xsTnC).

276 tituting native TnC with either cardiac TnC (cTnC), a site I-inactive skeletal TnC mutant (xsTnC), or

277 terminal deletion mutant was able to bind to cTnC, as shown by urea-polyacrylamide gel-shift analysis

278 sin cross bridges and direct Ca2+ binding to cTnC (cardiac and slow skeletal troponin C) in skinned f

279 ation results from altered Ca(2+)-binding to cTnC.

280 by mechanisms that do not involve binding to cTnC.

281 tween the cross-bridge and Ca(2+) binding to cTnC.

282 ments to calmidazolium (CDZ), which binds to cTnC and increases its affinity for Ca2+, sensitized for

283 Using a fluorescent probe coupled to cTnC (C35S-IANBD), the Ca(2+)-cTn binding affinity and C

284 Thus, the binding of cTnI to cTnC is a prerequisite to achieve a Ca(2+)-induced open

285 terminal extension to the binding of cTnI to cTnC.

286 y and in a concentration-dependent manner to cTnC.

287 Probe angle reflects underlying cTnC orientation.

288 When cTnC was inactivated through mutations of key residues w

289 when exchanged into fiber bundles from which cTnC had been extracted.

290 troscopy to study cTnI[1-73] in complex with cTnC.

291 with the phosphorylated cTnI complexed with cTnC in different ionic conditions.

292 r23/24 to alter the interaction of cTnI with cTnC in the troponin complex and is critical to the regu

293 ence of Ca(2+), neither drug interacted with cTnC.

294 ibitory region of cTnI from interacting with cTnC to interacting with actin.

295 This may result in altered interactions with cTnC and could explain the increased rate and decreased

296 nding of cTnI at the end that interacts with cTnC.

297 f either WT cTnI or each of the mutants with cTnC, reconstituted the complex into the cTnT-treated my

298 of F(max) while in fibres reconstituted with cTnC or xsTnC, reconstituted maximal force (rF(max)) was

299 In contrast, reconstitution with cTnC or xsTnC reduced maximal k(tr) to 0.48 and 0.44 of

300 Reconstitution with cTnC reduced maximal force (F(max)) by approximately 1/3