Purification and kinetic characterisation of human erythrocyte actin

Human erythrocyte actin can be extracted from membrane ghosts by low ionic strength treatment in the presence of protective amounts of calcium and ATP. Purification then involves a single chromatographic step. The erythrocyte actin can be labelled with N-(1-prenyl)iodoacetamide. The fluorescence enhancement which accompanies polymerisation can be used to determine the critical concentration for assembly and to follow the polymerisation reaction time-course. The polymerisation kinetics of erythrocyte actin are compared with those of rabbit skeletal muscle actin. The two are shown to be markedly different.