structural:expansion
Type V secretion system (T5SS)

Also called the autotransporter system, type V secretion involves use of the Sec system for crossing the inner membrane. Proteins which use this pathway have the capability to form a beta-barrel with their C-terminus which inserts into the outer membrane, allowing the rest of the peptide (the passenger domain) to reach the outside of the cell. Often, autotransporters are cleaved, leaving the beta-barrel domain in the outer membrane and freeing the passenger domain. Some researchers believe remnants of the autotransporters gave rise to the porins which form similar beta-barrel structures. A common example of an autotransporter that uses this secretion system is the Trimeric Autotransporter Adhesins.