Regulation of smooth muscle myosin.
It is well established that light chain phosphorylation is required before a smooth muscle can generate force. The apparent modulation of shortening velocity by phosphorylation during sustained contractions may be accounted for by a mechanical interaction between rapidly cycling phosphorylated crossbridges and slowly or non-cycling dephosphorylated crossbridges. Latchbridges, force-producing dephosphorylated crossbridges, have been proposed to explain why force levels remain high at low levels of phosphorylation. The role of the thin-filament-associated proteins caldesmon and calponin in regulation remains enigmatic, but their inhibitory properties in solution would be consistent with a possible involvement in maintenance of a relaxed state.
Trybus
K M
KM
Rosenstiel Research Center, Brandeis University, Waltham, MA 02254.
D000199:Actins / Q000502:physiology; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D004789:Enzyme Activation / Q000502:physiology; D009124:Muscle Proteins / Q000502:physiology; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism*; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D009218:Myosins / Q000378:metabolism*; D010766:Phosphorylation; D011487:Protein Conformation
D000199:Actins; D009124:Muscle Proteins; D009219:Myosin-Light-Chain Kinase; D000251:Adenosine Triphosphatases; D009218:Myosins