MUTUAL SENSITIZATION OF ATP AND GTP IN DRIVING F-ACTIN ON THE SURFACE-FIXED H-MEROMYOSIN

Using an in vitro motility assay on acto-H-meromyosin, we studied the sliding velocity of an actin filament driven by two kinds of H-meromyo sin heads: H-meromyosin head with ATP bound (fast motor) and with GTP bound (slow motor). We found a significant increase in the sliding vel ocity owing to the coexistence of the fast motor and the slow motor. T his phenomenon may give an important suggestion with regard to the int egration over multiple interactions of H-meromyosin heads along the ac tin filament.