| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Biophys J, August 2002, p. 1039-1049, Vol. 83, No. 2
Department of Biochemistry, Brody School of Medicine at East Carolina University, Greenville, North Carolina 27858-4354 USA
The interaction of myosin subfragment 1 (S1) with
actin-tropomyosin-troponin (regulated actin) is highly nucleotide
dependent. The binding of S1 or S1-ADP (but not S1-ATP nor
N,N'-
-phenylenedimaleimide-modified S1-ATP) to regulated actin activates ATP hydrolysis even in the absence
of Ca2+. Investigations with S1 and S1-ADP have led to the
idea that some actin sites are directly blocked toward the binding of
S1 either by tropomyosin or troponin. The blocked state is thought to
occur only at ionic strengths greater than 50 mM. The question is
whether nonactivating S1 binding is blocked under the same conditions.
We show that troponin inhibits binding of the nonactivating state,
N,N'--phenylenedimaleimide-S1-ATP, to
actin but only when tropomyosin is absent. A lag in the rate of binding
of activating S1 to actin (an indicator of the blocked state) occurs
only in the presence of tropomyosin. Thus, tropomyosin inhibits binding of rigor S1 but not S1-ATP-like states. No evidence for an ionic strength-dependent change in the mechanism of regulation was observed either from measurements of the rate of activating S1 binding or from
the equilibrium binding of nonactivating S1 to actin. At all conditions
examined,
N,N'--phenylenedimaleimide-S1-ATP bound to regulated actin in the absence of Ca2+. These
results support the view of regulation in which tropomyosin movement is
an allosteric switch that is modulated by activating myosin binding but
that does not function solely by regulating myosin binding.
Biophys J, August 2002, p. 1039-1049, Vol. 83, No. 2
© 2002 by the Biophysical Society 0006-3495/02/08/1039/11 $2.00
This article has been cited by other articles:
 |
|
 |
|
  M. Sliwinska, R. Skorzewski, and J. Moraczewska Role of Actin C-Terminus in Regulation of Striated Muscle Thin Filament Biophys. J., February 15, 2008; 94(4): 1341 - 1347. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Maytum, V. Hatch, M. Konrad, W. Lehman, and M. A. Geeves Ultra Short Yeast Tropomyosins Show Novel Myosin Regulation J. Biol. Chem., January 25, 2008; 283(4): 1902 - 1910. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Gunning, G. O'neill, and E. Hardeman Tropomyosin-Based Regulation of the Actin Cytoskeleton in Time and Space Physiol Rev, January 1, 2008; 88(1): 1 - 35. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Shitaka, C. Kimura, and M. Miki The Rates of Switching Movement of Troponin T between Three States of Skeletal Muscle Thin Filaments Determined by Fluorescence Resonance Energy Transfer J. Biol. Chem., January 28, 2005; 280(4): 2613 - 2619. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Gafurov, Y.-D. Chen, and J. M. Chalovich Ca2+ and Ionic Strength Dependencies of S1-ADP Binding to Actin-Tropomyosin-Troponin: Regulatory Implications Biophys. J., September 1, 2004; 87(3): 1825 - 1835. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Moraczewska, J. Gruszczynska-Biegala, M. J. Redowicz, S. Yu. Khaitlina, and H. Strzelecka-Golaszewska The DNase-I Binding Loop of Actin May Play a Role in the Regulation of Actin-Myosin Interaction by Tropomyosin/Troponin J. Biol. Chem., July 23, 2004; 279(30): 31197 - 31204. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Maytum, F. Bathe, M. Konrad, and M. A. Geeves Tropomyosin Exon 6b Is Troponin-specific and Required for Correct Acto-myosin Regulation J. Biol. Chem., April 30, 2004; 279(18): 18203 - 18209. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. J. Heller, M. Nili, E. Homsher, and L. S. Tobacman Cardiomyopathic Tropomyosin Mutations That Increase Thin Filament Ca2+ Sensitivity and Tropomyosin N-domain Flexibility J. Biol. Chem., October 24, 2003; 278(43): 41742 - 41748. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
