pACYC184 can be used together with, or as an alternative multipurpose vector to, pBR322. The origin of replication of pACYC184 is derived from the miniplasmid p15A1, whereas that of pBR322 and its derivatives is from pColE. These origins are compatible and pACYC184 and pBR322 can therefore co-exist within the same cell. This allows two recombinant plasmids to be maintained and expressed simultaneously.