Oligomeric states of the SecA and SecYEG core components of the bacterial Sec translocon

Many proteins synthesized in the cytoplasm ultimately function in non-cytoplasmic locations. In Escherichia coli, the general secretory (Sec) pathway transports the vast majority of these proteins. Two fundamental components of the Sec transport pathway are the SecYEG heterotrimeric complex that forms the channel through the cytoplasmic membrane, and SecA, the ATPase that drives the preprotein to and across the membrane. This review focuses on what is known about the oligomeric states of these core Sec components and how the oligomeric state might change during the course of the translocation of a preprotein.