This family consists of homologues of Sec61beta - a component of the Sec61/SecYEG protein secretory system. The domain is found in eukaryotes and archaea and is possibly homologous to the bacterial SecG. It consists of a single putative transmembrane helix, preceded by a short stretch containing various charged residues; this arrangement may help determine orientation in the cell membrane [1].

1: Sec61beta - a component of the archaeal protein secretory system. Kinch LN, Saier MH Jr, Grishin NV; Trends Biochem Sci 2002;27:170-171. PMID:11943537