Abstract: Disclosed are DNA sequences comprising structural genes coding for (1) a polypeptide having the amino acid sequence and properties of urogastrone and for (2) polypeptide analogs thereof which differ in terms of the identity and/or location of one or more amino acids, e.g., [Asp.sup.25 ] and Pro.sup.52, Pro.sup.53 ] analogs of urogastrone. Structural gene sequences may be provided with initial and terminal sequences which facilitate production of discrete protein products by selected host microorganisms as well as for expression by host organisms of fusion proteins, e.g., .beta.-lactamase-urogastrone and .beta.-galactosidase-urogastrone from which the desired products may be isolated.

Abstract: Disclosed are novel DNA sequences operative as promoters of microbial transcription of structural genes and comprising synthetic E.coli bacteriophage T5 "early" promoter replica DNA sequences. Disclosed also are novel promoter/operator DNA sequences comprising a synthetic T5 early promoter replica DNA sequence associated with a regulatable operator DNA sequence providing for selectively regulatable transcription of structural genes in, e.g., E.coli cells transformed with a DNA vector including same.