Figure 6-3: An ATPase ratchet model of DNA translocation in T3. A gp19 ATPase subunit positioned on the connector interacts with the phosphate backbone of the DNA (a). Upon hydrolysis of ATP, the gp19 monomer changes conformation (b), driving the DNA through the connector and into the prohead. This translocation event brings the backbone into alignment with the next consecutive ATPase monomer (c) to initiate the next translocation event (d). Reproduced from Fujisawa and Morita, 1997, with permission.