Most VirB proteins help in the formation of the membrane channel or act as ATPases to provide energy for assembly and export processes of channel. VirB proteins, including VirB2, VirB5 and VirB7 help in the formation of the T-pilus. VirB2 is the major pilin protein that undergoes processing and cyclization.
Ss-TDNA is coated with VirE2, a non-sequence specific single stranded DNA binding protein.
Vir D2 and Vir E2 protect the ss-T strand from nucleases inside the plant cytoplasm by attaching to the 5'end. Both VirD2 and VirE2 proteins have nuclear localization signals (NLS) which serves as pilot proteins to guide the mature T-complex to the plant nucleus.
The efficiency of transfer is enhanced by VirC2 proteins, which recognize and bind to the overdrive enhancer element.
Some additional proteins like importins, VIP1 and VirF may interact with the T-strand, either directly or indirectly, to form larger T-complexes in the plant cell. Vir F directs the proteins coating T-complex (VIP1 and Vir E2) for destruction in proteasome.
Inside the nucleus, ss-TDNA is converted into ds-TDNA which gets integrated into the plant genome via process called illegitimate recombination.