 The * represents a reorientation between two domains of each subunit that occurs in the dissociated state because it is sterically forbidden in the larger multimers.PBGS is encoded by a single gene and each PBGS multimer is composed of multiple copies of the same protein.Each PBGS subunit consists of a ~300 residue αβ-barrel domain, which houses the enzyme's active site in its center, and a >25 residue N-terminal arm domain.