Résumé
The Sec machinery facilitates protein translocation membrane insertion and into biological membranes of organisms from all three domains of life. The mechanism of the cotranslational mode of translocation is conserved across the domains, whereas the components involved in posttranslational translocation differ. In addition, significant differences are observed in the composition of the Sec machinery within the bacterial domain. Here, we will review these differences in an evolutionary context, and discuss the latest insights into the structure and dynamics of the translocon and the bacterial motor protein SecA, with emphasis on their oligomeric state(s) during protein translocation.