Bacterial expression of porcine growth hormone

A plasmid for the production of porcine growth hormone or an analog thereof which upon introduction into a suitable bacterial host containing the thermolabile repressor CI renders the host cell capable, upon increasing the temperature of the host cell to a temperature at which the repressor is destroyed, of effecting expression of DNA encoding porcine growth hormone and production of porcine growth hormone or analogs thereof. The plasmid is a double-stranded DNA molecule which includes in 5' to 3' the following: a DNA sequence which contains the promoter and operator PLOL from lambda bacteriophage; the N utilization site for binding antiterminator N protein produced by the host cell; a DNA sequence which contains a ribosomal binding site for rendering the mRNA of the gene encoding porcine growth hormone capable of binding to ribosomes within the host cell; an ATG initiation codon; a restriction enzyme site for inserting the gene encoding porcine growth hormone into the plasmid in phase with the ATG initiation codon; a gene encoding porcine growth hormone; and additionally a DNA sequence which contains an origin of replication from a bacterial plasmid capable of autonomous replication in the host cell and a DNA sequence which contains a gene associated with a selectable or identifiable trait which is manifested when the plasmid is present in the host cell.