The Sec61/SecY translocon mediates translocation of proteins across the membrane and integration of membrane proteins into the lipid bilayer. The structure of the translocon revealed a plug domain blocking the pore on the lumenal side.The plug is unlikely to be important for sealing the translocation pore in yeast but it plays a role in stabilising Sec61p during translocon formation. The domain runs from residues 52-74 [1].

1: The plug domain of yeast Sec61p is important for efficient protein translocation, but is not essential for cell viability. Junne T, Schwede T, Goder V, Spiess M; Mol Biol Cell. 2006;17:4063-4068. PMID:16822836