Protection Against Osmotic Stress by cGMP-Mediated Myosin Phosphorylation

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Science  12 Jan 1996:
Vol. 271, Issue 5246, pp. 207-209
DOI: 10.1126/science.271.5246.207


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.