HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Marston, S. B. Articles by Huber, P. A. Search for Related Content PubMed PubMed Citation Articles by Marston, S. B. Articles by Huber, P. A. Social Bookmarking                      What's this?

J. Biol. Chem., Vol. 269, Issue 51, 32104-32109, 12, 1994

Smooth muscle caldesmon controls the strong binding interaction between actin-tropomyosin and myosin

SB Marston, ID Fraser and PA Huber
Department of Cardiac Medicine, National Heart and Lung Institute, London, United Kingdom.

We have demonstrated that caldesmon does not alter the affinity of weak binding actomyosin complexes when it inhibits actin-tropomyosin activation at physiological ratios (1 per 14 actins), and we proposed that it acts upon the strong binding complexes in the same way that troponin-tropomyosin does. We therefore compared the effect of caldesmon, caldesmon fragments, and troponin upon the interaction of the strongly bound complexes S-1.ADP, S-1.adenylyl imidodiphosphate (AMP.PNP), and N-ethylmaleimide-treated myosin subfragment-1 (NEM-S-1) with actin-tropomyosin. In 0.17 M ionic strength buffer [14C]iodoacetamide-labeled S1.ADP bound to actin-smooth muscle tropomyosin with no evidence of cooperativity; Kd = 0.8 +/- 0.3 microM (n = 5). Inhibitory concentrations of sheep aorta caldesmon or rabbit skeletal muscle troponin made the binding highly cooperative. At low levels of saturation the apparent Kd was 10-40 microM with 10 microM caldesmon and 8-20 microM with 6 microM troponin; at > 50% saturation the binding was indistinguishable from actin-tropomyosin alone. A similar result was obtained for the binding of [14C]iodoacetamide- labeled S-1.AMP.PNP to actin-smooth muscle tropomyosin at 0.03 M ionic strength (Kd = 0.47 +/- 0.05 microM). Binding was slightly cooperative and became highly cooperative in the presence of inhibitory concentrations of troponin, caldesmon, and the human caldesmon fragments H7 (amino acids 622-767) and H9 (amino acids 726-793). We conclude that caldesmon and troponin both act as allosteric effectors of the "on"/"off" equilibrium of actin-tropomyosin. 0.1 NEM-S-1/actin potentiated actin-smooth muscle tropomyosin activation of myosin MgATPase 7-fold at 0.03 M ionic strength. Caldesmon inhibited the ATPase in the presence and absence of 0.5 microM NEM-S-1. NEM-S-1 reactivated actin-tropomyosin, which had been inhibited by troponin, caldesmon, H7, or H9. This is compatible with opposing effects of NEM-S- 1 and caldesmon or troponin upon the actin-tropomyosin on/off equilibrium.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				S. Ansari, M. Alahyan, S. B. Marston, and M. EL-Mezgueldi Role of Caldesmon in the Ca2+ Regulation of Smooth Muscle Thin Filaments: EVIDENCE FOR A COOPERATIVE SWITCHING MECHANISM J. Biol. Chem., January 4, 2008; 283(1): 47 - 56. [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]

				M. Alahyan, M. R. Webb, S. B. Marston, and M. EL-Mezgueldi The Mechanism of Smooth Muscle Caldesmon-Tropomyosin Inhibition of the Elementary Steps of the Actomyosin ATPase J. Biol. Chem., July 14, 2006; 281(28): 19433 - 19448. [Abstract] [Full Text] [PDF]

				H. Teoh, M. Zacour, A. D. Wener, L. Gunaratnam, and M. E. Ward Increased myofibrillar protein phosphatase-1 activity impairs rat aortic smooth muscle activation after hypoxia Am J Physiol Heart Circ Physiol, April 1, 2003; 284(4): H1182 - H1189. [Abstract] [Full Text] [PDF]

				M. E. Zacour, H. Teoh, A. J. Halayko, and M. E. Ward Mechanisms of aortic smooth muscle hyporeactivity after prolonged hypoxia in rats J Appl Physiol, June 1, 2002; 92(6): 2625 - 2632. [Abstract] [Full Text] [PDF]

				S. Zhuang, K. Mabuchi, and C.-L. A. Wang Heat Treatment Could Affect the Biochemical Properties of Caldesmon J. Biol. Chem., November 22, 1996; 271(47): 30242 - 30248. [Abstract] [Full Text] [PDF]

				M. EL-Mezgueldi and StevenB. Marston The Effects of Smooth Muscle Calponin on the Strong and Weak Myosin Binding Sites of F-actin J. Biol. Chem., November 8, 1996; 271(45): 28161 - 28167. [Abstract] [Full Text] [PDF]

				I. D. C. Fraser and S. B. Marston In Vitro Motility Analysis of Smooth Muscle Caldesmon Control of Actin-Tropomyosin Filament Movement J. Biol. Chem., August 25, 1995; 270(34): 19688 - 19693. [Abstract] [Full Text] [PDF]