The interaction of equine platelet tropomyosin with skeletal muscle actin.
Abstract: Whereas skeletal muscle tropomyosin binds strongly to muscle F-actin in a buffer containing 30 mM KCl and 1-2 mM free Mg2+, equine platelet tropomyosin only binds stoichiometrically (1 tropomyosin molecule per 6 actin monomers) at higher Mg2+ concentrations (7-8 mM free Mg2+). At low free Mg2+ concentrations (1.5 mM) the binding of the platelet protein is only marginally increased by raising the KCl concentration to an optimal value (0.10-0.20 M). This weaker binding can be attributed to the relatively poor head-to-tail polymerization of platelet tropomyosin and its fewer actin-binding sites. In a buffer containing 30 mM KCl and 3 mM Mg2+, the binding of platelet tropomyosin to F-actin can be induced by the addition of either skeletal muscle myosin subfragment 1 or troponin-I. The binding induced by troponin-I is largely neutralized by the addition of troponin-C both in the presence and absence of Ca2+, but by calmodulin only in the presence of Ca2+.
Publication Date: 1981-07-25 PubMed ID: 6894754
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research article focuses on the study of how equine platelet tropomyosin interacts with skeletal muscle actin and the factors such as presence of KCl, Mg2+ and other proteins like skeletal muscle myosin subfragment 1 and troponin-I that can influence this interaction.
Detailed Explanation:
- The paper begins with the assertion that while skeletal muscle tropomyosin has a strong bond with muscle F-actin when subjected to a buffer containing 30mM KCl and 1-2mM free Mg2+, the equine platelet tropomyosin’s bond with actin shows different behaviour. This bond is only stoichiometric (meaning the ratio of actin monomers to tropomyosin molecules is 6 to 1) when the concentration of Mg2+ is higher, specifically around 7-8mM.
- Furthermore, it was noticed that at low concentrations of Mg2+ (1.5mM), even after increasing the KCl concentration to an optimal range (0.10-0.20M), the platelet protein binding is marginally increased only. The weaker binding can be attributed to the poor polymerization of the platelet tropomyosin from head-to-tail and its fewer actin binding sites.
- In addition, through experimentation the research illustrates that when the solution consists of a buffer with 30mM KCl and 3mM Mg2+, platelet tropomyosin’s binding to F-actin can be induced with either skeletal muscle myosin subfragment 1 or with troponin-I.
- The binding that was induced by troponin-I could be largely neutralized with troponin-C irrespective of the presence or absence of Ca2+. However, if the neutralizing agent was calmodulin, it was effective only in the presence of Ca2+.
This research sets ground for future research into the specific interactions of the tropomyosin molecule with actin, which is significant for understanding the functioning of muscles and may have implications for treatments of muscle dysfunction. The findings also underscore the importance of different molecular conditions for the interaction of these proteins.
Cite This Article
APA
Côté GP, Smillie LB.
(1981).
The interaction of equine platelet tropomyosin with skeletal muscle actin.
J Biol Chem, 256(14), 7257-7261.
Publication
Researcher Affiliations
MeSH Terms
- Actins / metabolism
- Animals
- Blood Platelets / metabolism
- Horses
- Kinetics
- Macromolecular Substances
- Magnesium / pharmacology
- Muscles / metabolism
- Potassium Chloride / pharmacology
- Protein Binding
- Rabbits
- Tropomyosin / blood
Citations
This article has been cited 19 times.- Colpan M, Moroz NA, Kostyukova AS. Tropomodulins and tropomyosins: working as a team.. J Muscle Res Cell Motil 2013 Aug;34(3-4):247-60.
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- Bradac JA, Gruber CE, Forry-Schaudies S, Hughes SH. Isolation and characterization of related cDNA clones encoding skeletal muscle beta-tropomyosin and a low-molecular-weight nonmuscle tropomyosin isoform.. Mol Cell Biol 1989 Jan;9(1):185-92.
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- Hegmann TE, Lin JL, Lin JJ. Motility-dependence of the heterogenous staining of culture cells by a monoclonal anti-tropomyosin antibody.. J Cell Biol 1988 Feb;106(2):385-93.
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- Xie L, Hirabayashi T, Miyazaki J. Histological distribution and developmental changes of tropomyosin isoforms in three chicken digestive organs.. Cell Tissue Res 1992 Sep;269(3):391-401.
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