The pGEM®-9Zf(–) Vector is a recombinant plasmid designed to provide a versatile range of cloning strategies, and contains T7 and SP6 RNA polymerase promoters flanking a multiple cloning region within the α-peptide coding region of β-galactosidase. Insertional inactivation of the α-peptide identifies recombinant clones by color screening on indicator plates when using appropriate E. coli strains (e.g., JM109). The multiple cloning region is unique and includes restriction sites for NsiI, SpeI, HindIII, XbaI, EcoRI, SalI and SacI.