Subunit of the protein translocation channel SecYEG (By similarity). While not essential, it considerably increases the export efficiency of extracellular proteins. Component of the Sec protein translocase complex. Heterotrimer consisting of SecY, SecE and SecG subunits. The heterotrimers can form oligomers, although 1 heterotrimer is thought to be able to translocate proteins. Interacts with SecDF, and other proteins may be involved. The channel interacts with SecA via subunit SecY (By similarity). Also part of the accessory SecA2/SecY2 protein translocation apparatus required to export cell wall protein GspB. Grows normally, a double secG/secY2 mutant enters stationary phase earlier. Significant differences in the export pattern of a number of extracellular proteins are seen in a secG deletion; the double secG/secY2 mutant exacerbates this effect (shown in RN4220). Single or double deletions are as virulent as wild-type (shown in RN4220 and SH1000). Belongs to the SecG family.