Expression of cloned calf prochymosin gene sequence in Escherichia coli

An expression plasmid for calf prochymosin (prorennin) cDNA was constructed. The plasmid (pCR301) contains the lacUV5 promoter in front of the fused gene in which the codons for the N-terminal four amino acids of prochymosin cDNA were replaced with those for the N-terminal ten amino acids of beta-galactosidase. Synthesis of the fused protein with the expected Mr was detected immunologically in Escherichia coli harboring pCR301. The product seemed to be localized in the cell membrane of the bacterial host.