G-actin modified by plasma membrane interaction polymerizes only in the presence of filamentous myosin

In non-muscle cells actin can occur in different forms depending on the immediate and local needs of the cell. This suggests the presence of regulatory mechanisms capable to allow an easy interconversion between polymerization states of actin ranging from functional microfilaments to oligomeric or even monomeric actin. We describe here a potential regulatory mechanism mediated by the interaction of G-actin with plasma membranes. After the interaction G-actin is modified insuch a way that it does not polymerize in the presence of 2 mM MgCl, but only in the presence ‘of myosin with the formation of contractile units.