Key result
Myosin phosphorylated only on Thr-18 has approximately 15-fold lower actin-activated ATPase activity than myosin phosphorylated on Ser-19, yet moves actin filaments at similar velocities.
Population
Recombinant Xenopus regulatory light chains (RLCs) and smooth muscle myosin hybrids
Comparison
Alanine substitutions of Ser-19 and Thr-18 and… vs Wild-type Xenopus RLCs and myosin phosphorylated…
Design
Preclinical
Authors
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Highlights decoupled myosin properties for mechanistic studies; leaves open translation to cardiovascular smooth muscle function.
Phosphorylation on Thr-18 of the regulatory light chain dissociates the ATPase and motor properties of smooth muscle myosin II, allowing filament movement despite low ATPase activity.
Bresnick et al. (1995) studied this question. Alanine substitutions of Ser-19 and Thr-18 in Xenopus regulatory light chain vs. Wild-type Xenopus RLC / gizzard RLC was evaluated on Actin-activated ATPase activity and in vitro motility. Myosin phosphorylated only on Thr-18 has approximately 15-fold lower actin-activated ATPase activity than myosin phosphorylated on Ser-19, yet moves actin filaments at similar velocities.
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