New improved lacZ gene fusion vectors.

New plasmid vectors suitable for creating fusions with the lacZ gene have been developed. These vectors represent an improvement over currently available vectors and possess the following features: (1) an undetectable background beta-galactosidase (beta Gal) activity in the absence of fusion, (2) an extended multiple cloning site (MCS), and (3) the ability to conveniently subclone in any one of three translational frames. Medium- and high-copy-number versions of these vectors have been developed.