Phage L5 integrating vectors are present within the Mycobacterial Cell in an equilibrium between integrated and excised states.

Integrating mycobacterial plasmids containing the phage L5 attachment site (attP) are able to insert into the mycobacterial chromosome attB site. Plasmids containing the attP site and chromosome containing the attB site are present in equilibrium between the inserted and the excised states in the presence of the phage L5 integrase.