DESTABILIZING EFFECT OF CALCIUM ON MICROTUBULES IN-VITRO

The extent of disassembly of microtubules induced by calcium has been determined at various temperatures. The effect of calcium increases wi th decreasing temperature. Length distributions of microtubules were m easured before and after partial disassembly under the influence of ca lcium and in steady state in the presence of calcium. Partial disassem bly due to calcium resulted in shorter microtubules indicating endwise disassembly. Calcium in steady state induced an increase of length im plying that the influence of microtubule associated proteins (MAPs) is suppressed and that dynamic instability is pronounced.