Calcium control of Saccharomyces cerevisiae actin assembly.
Low levels of Ca2+ dramatically influence the polymerization of Saccharomyces cerevisiae actin in KCl. The apparent critical concentration for polymerization (C infinity) increases eightfold in the presence of 0.1 mM Ca2+. This effect is rapidly reversed by the addition of ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid or of 0.1 mM Mg2+. Furthermore, the addition of Ca2+ to polymerized actin causes a reversible increase in the apparent C infinity. In the presence of Ca2+, at actin concentrations below the apparent C infinity, particles of 15 to 50 nm in diameter are seen instead of filaments. These particles are separated from soluble actin when Ca2+-treated filamentous actin is sedimented at high speed; both the soluble and particulate fractions retain Ca2+-sensitive polymerization. The Ca2+ effect is S. cerevisiae actin-specific: the C infinity for rabbit muscle actin is not affected by the presence of Ca2+ and S. cerevisiae actin. Ca2+ may act directly on S. cerevisiae actin to control the assembly state in vivo.
D000199:Actins / Q000378:metabolism*; D002118:Calcium / Q000502:physiology*; D003599:Cytoskeleton / Q000648:ultrastructure; D008274:Magnesium / Q000502:physiology; D008854:Microscopy, Electron; D009124:Muscle Proteins / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000502:physiology*
D000199:Actins; D009124:Muscle Proteins; D011189:Potassium Chloride; D008274:Magnesium; D002118:Calcium