Length distribution of F-actin in Dictyostelium discoideum.

摘要: Inhibition of deoxyribonuclease I activity was used to assay the actin monomers and pointed ends filaments in lysates Dictyostelium discoideum. The KD for binding reaction 0.2-0.3 nM. Total cellular 93 microM (approximately 0.1 fmol/cell) which roughly half initially polymeric. Essentially all filamentous (F-actin) readily pelleted microcentrifuge therefore presumed be cytoskeleton. Free F-actin barbed ends, measured as pelletable [3H]cytochalasin B, numbered 1.8 x 10(5)/cell; nuclei polymerization rabbit muscle globular (monomeric) 2.0 determined by their inhibition I, 3.6 10(5)/cell. These values suggest that might occluded. On average, contained approximately 76 subunits were about 0.2 micron long. distribution lengths estimated from time course depolymerization following vast dilution. Three populations defined. In one experiment, smallest population 71% mass 96% ends; these averaged 80 or 0.22 microns length. An intermediate 14% 3% filaments; 460 (1.3 microns) largest 15% 0.3% 13 length, diameter cell. numerous short populate a cortical mesh, while long constitute endoplasmic bundles.