4dq9 is a 2 chain structure with sequence from Vibrio cholerae. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
GSPH_VIBCH Involved in a type II secretion system (T2SS, formerly general secretion pathway, GSP) for the export of proteins (By similarity). Required for secretion of cholera toxin through the outer membrane.