Key result
Phosphorylation of rabbit skeletal muscle myosin P-light-chain resulted in an apparent 2-fold decrease in the Km for actin (from ~6 microM to ~2.5 microM) with no significant effect on Vmax.
Population
Purified rabbit skeletal muscle myosin
Comparison
Phosphorylation by calmodulin-dependent myosin… vs Unphosphorylated state
Design
Preclinical
Authors
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No immediate clinical implications for cardiovascular disease; leaves open applicability of homogeneous myosin kinetics to cardiac muscle.
Effect estimate: 2-fold decrease
Absolute Event Rate: 2.5% vs 6%
Phosphorylation of rabbit skeletal muscle myosin decreases the Km for actin without affecting Vmax, suggesting cooperative interactions between myosin heads do not play an important role in skeletal muscle activation.
Persechini et al. (1984) studied this question. Phosphorylation of P-light-chain vs. Unphosphorylated myosin was evaluated on Km for actin in actin-activated ATPase activity (2-fold decrease). Phosphorylation of rabbit skeletal muscle myosin P-light-chain resulted in an apparent 2-fold decrease in the Km for actin (from ~6 microM to ~2.5 microM) with no significant effect on Vmax.
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