Figure 1.

Schematic of the generation of somatostatin-directed plasmid employed in the transfection E. coli to produce human somatostatin. The chemically synthesized gene for somatostatin was inserted into the E. coli beta-galactosidase gene (ß-gal) on the plasmid pBR322. In E. coli, this plasmid directs the synthesis of a chimeric protein that can be cleaved in vitro at methionine residues by cyanogen bromide to yield active somatostatin. Abbreviations: DNA, deoxyribonucleic acid; Lac, lactose operon; P, lac promoter; O, lac operator; Som, somatostatin Adapted from Itakura K, et al. Expression of Escherichia coli of a chemically synthesized gene for the hormone somatostatin. Science. 1977;198(4321):1056-1063, with the kind permission of the publisher.