Abstract
Conventional myosin functions universally as a generator of motive force in eukaryotic cells. Analysis of mutants of the microorganism Dictyostelium discoideum revealed that myosin also provides resistance against high external osmolarities. An osmo-induced increase of intracellular guanosine 3',5'-monophosphate was shown to mediate phosphorylation of three threonine residues on the myosin tail, which caused a relocalization of myosin required to resist osmotic stress. This redistribution of myosin allowed cells to adopt a spherical shape and may provide physical strength to withstand extensive cell shrinkage in high osmolarities.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Actin Cytoskeleton / chemistry
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Actins / analysis
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Animals
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Cyclic GMP / analogs & derivatives
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Cyclic GMP / metabolism*
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Cyclic GMP / pharmacology
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Cytoplasm / chemistry
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Dictyostelium / genetics
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Dictyostelium / physiology*
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Dictyostelium / ultrastructure
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Glucose / pharmacology
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Guanylate Cyclase / metabolism
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Myosins / analysis
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Myosins / metabolism*
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Osmotic Pressure
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Phosphorylation
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Pseudopodia / chemistry
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Pseudopodia / ultrastructure
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Threonine / metabolism
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Water-Electrolyte Balance
Substances
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Actins
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Threonine
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8-bromocyclic GMP
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Myosins
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Guanylate Cyclase
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Cyclic GMP
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Glucose