What question did this study set out to answer?

To determine the binding stoichiometry and cooperativity of caldesmon to actin and examine its inhibitory effect on myosin subfragment 1 ATPase activity in the presence and absence of tropomyosin.

June 1, 1989Journal of Biological ChemistryOpen Access

The binding of Caldesmon to Actin and Its Effect on the ATPase Activity of Soluble Myosin Subfragments in the Presence and Absence of Tropomyosin

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Population

In vitro biochemical model (actin, actin-tropomyosin, skeletal myosin subfragment 1, caldesmon)

Comparison

Caldesmon binding in the presence of tropomyosin vs Caldesmon binding in the absence of tropomyosin

Design

Preclinical

Authors

LVL VelazEast Carolina University MHMark E. HemricLiberty University CBC.E. BensonEast Carolina University

Discussion

Member takes

Implication

Provides mechanistic insight into smooth muscle regulation; leaves open translation to human cardiovascular disease.

Key Points

To determine the binding stoichiometry and cooperativity of caldesmon to actin and examine its inhibitory effect on myosin subfragment 1 ATPase activity in the presence and absence of tropomyosin.
Measured binding of radiolabeled 125I- and 14C-caldesmon to actin and actin-tropomyosin using a cosedimentation assay.
Analyzed binding kinetics with the McGhee and von Hippel lattice model and evaluated skeletal myosin subfragment 1 actin-activated ATPase activity along with Ca2+-calmodulin reversibility.
Caldesmon bound to actin at a stoichiometry of 1:7 to 1:10 with positive cooperativity (omega = 5-6), and tropomyosin increased the association constant from ~6 x 10(5) to ~1.4 x 10(6) M-1.
Caldesmon maximally inhibited actin-activated ATPase activity at a 1:7 caldesmon-to-actin ratio, producing stronger inhibition in the presence of tropomyosin than in its absence.
Binding of caldesmon to actin was fully reversed in the presence of Ca2+-calmodulin.

Structured PICO

Population

In vitro biochemical model (actin, actin-tropomyosin, skeletal myosin subfragment 1, caldesmon)

Intervention

Caldesmon binding in the presence of tropomyosin

Comparator

Caldesmon binding in the absence of tropomyosin

Outcome

Binding characteristics (stoichiometry, cooperativity, association constant) and ATPase activity inhibitionsurrogate

Caldesmon binds to actin with positive cooperativity and inhibits actin-activated ATPase activity, an effect enhanced by tropomyosin and reversed by Ca2+-calmodulin.

Cite This Study

Velaz et al. (1989) studied this question.

synapsesocial.com/papers/6a702ce7b27f158178273ae3 https://doi.org/10.1016/s0021-9258(18)60573-3

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The binding of Caldesmon to Actin and Its Effect on the ATPase Activity of Soluble Myosin Subfragments in the Presence and Absence of Tropomyosin

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

The binding of Caldesmon to Actin and Its Effect on the ATPase Activity of Soluble Myosin Subfragments in the Presence and Absence of Tropomyosin

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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