What question did this study set out to answer?

To investigate the molecular characteristics of smooth muscle calcium-activated protease and determine how limited autolysis affects its calcium sensitivity and subunit composition.

August 1, 1982Journal of Biological ChemistryOpen Access

Limited autolysis reduces the Ca2+ requirement of a smooth muscle Ca2+-activated protease.

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To investigate the molecular characteristics of smooth muscle calcium-activated protease and determine how limited autolysis affects its calcium sensitivity and subunit composition.
Purified calcium-activated protease from chicken gizzard smooth muscle, yielding approximately 15 mg of heterodimeric enzyme per 1 kg of fresh tissue.
Characterized autolytic conversion into altered subunit species and quantified degradation of [3H]-labeled 27,000-dalton cardiac myosin light chain substrates across varying calcium concentrations.
Exposure to calcium rapidly converted the 80,000/30,000-dalton heterodimer (form I) via simultaneous autolysis of both subunits into a 76,000/18,000-dalton species (form II) with identical calcium dependence (K0.5 = 300 microM).
Limited autolysis reduced the calcium requirement for substrate cleavage 30-fold from K0.5 = 150 microM for form I to K0.5 = 5 microM for form II without changing specific enzymatic activity.

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Implication

Biochemical analysis demonstrates that limited autolysis lowers the calcium requirement of smooth muscle protease 30-fold, suggesting a mechanism for physiological intracellular activation.

Cite This Study

Hathaway et al. (1982) studied this question.

synapsesocial.com/papers/6a7d531fda72e8de9c279a00 https://doi.org/10.1016/s0021-9258(18)34244-3

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Implication

Biochemical analysis demonstrates that limited autolysis lowers the calcium requirement of smooth muscle protease 30-fold, suggesting a mechanism for physiological intracellular activation.

Limited autolysis reduces the Ca2+ requirement of a smooth muscle Ca2+-activated protease.

Key Points

Discussion

Implication

Cite This Study

Limited autolysis reduces the Ca2+ requirement of a smooth muscle Ca2+-activated protease.

Key Points

Discussion

Implication

Cite This Study

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