A REFINED VECTOR SYSTEM FOR THE IN-VITRO CONSTRUCTION OF SINGLE-COPY TRANSCRIPTIONAL OR TRANSLATIONAL FUSIONS TO LACZ

New single-copy vectors based on lambda phage have been developed for creating either transcriptional (operon) or translational (gene) fusio ns to the lacZ gene. The improvements of these vectors over the previo us lambda TL61 vector include: (i) incorporation of a tetracycline-res istance-encoding gene (Tc-R) to permit direct selection of lysogens, ( ii) low-background beta-galactosidase activity, (iii) the ability to a ccept DNA inserts up to 8 kb in size, and (iv) an expanded multiple cl oning site (MCS). The new transcriptional fusion vector retains the RN ase III processing site downstream from the MCS which ensures independ ent translation of lacZ. The set of three translational fusion vectors allow for convenient subcloning in any of the three translational rea ding frames.