Essential subunit of the Sec protein translocation channel SecYEG. Clamps together the 2 halves of SecY. May contact the channel plug during translocation. 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 the ribosome. Interacts with SecDF, and other proteins may be involved. Interacts with SecA. Belongs to the SecE/SEC61-gamma family. Extended N-terminus.