File:Type IV Pilus Twitching Motility Steps.svg

Pre-PilA is made in the cytoplasm and moves into the inner membrane. Pre-PilA is inserted into the inner membrane. PilD, a peptidase, removes a leader sequence, thus making the Pre-Pila shorter and into PilA, the main building-block protein of Pili. PilF, a NTP-Binding protein that provides energy for Type IV Pili Assembly. The secretin protein, PilQ, found on the outer membrane of the cell is necessary for the development/extension of the pilus. PilC is the first proteins to form the pilus and are responsible for overall attachment of the pilus. Once the Type IV Pilus attaches or interacts with what it needs to, it begins to retract. This occurs with the PilT beginning to degrade the last parts of the PilA in the pilus. The mechanism of PilT is very similar to PilF.