text: The p3 protein is anchored to one end of the virion by the C-terminal domain of p3. Infection of host bacteria involves interaction of two different N-terminal regions of p3 with two different sites of the host bacteria. First, the N2 domain of p3 attaches to the outer tip of the F-pilus, and the pilus retracts into the cell. This retraction may involve depolymerization of the pilus subunit assembly into the cell membrane at the base of the pilus by a reversal of the pilus growth and polymerization process. As the tip of the pilus bearing p3 approaches the cell wall, the N1 domain of p3 interacts with the bacterial TolQRA protein to complete infection and release the genome into the cytoplasm of the host.