FIGURE 2: Secretion systems used by C. trachomatis to transport proteins to different aqueous and membranaceous chlamydial and host cell compartments. It is unclear how some chlamydial T3S substrates are transported into the inclusion lumen or how Incs insert into the inclusion membrane. IMPs, chlamydial inner membrane proteins; PPs, chlamydial periplasmic proteins; OMPs, chlamydial outer membrane proteins. See list of abbreviations and main text for details.