A plasmid vector that allows fusion of the Escherichia coli galactokinase gene to the translation startpoint of other genes

By genetic manipulation of cloned Escherichia coli galactose operon DNA, we have constructed a new plasmid in which the N terminal segment of the galK gene is replaced by the N terminal of the galE gene. This plasmid encodes a hybrid protein that confers a Gal K+ phenotype on host cells: differences in initiation at the galE translation start point cause different phenotypes. The plasmid has unique restriction sites at the junction of the galE and galK gene segments and thus can be used to replace the N terminal of galK with any other translation start.