Abstract
A bacteriophage lambda cloning vector carrying the trp/lacW205 substitution is described. The vector facilitates the fusion in vitro of genetic control signals to the lacZ structural genes of Escherichia coli. This system was used to define transcriptional termination sites in the lambda b2 region. This region contains termination sites that are unresponsive to the λ antiterminating proteins pQ and pN.