The Seminal Vesicle Secretion IV Gene: Detection of S1 Nuclease-Sensitive Sites in Supercoiled Plasmid pSVS 3.3

We have investigated the sites sensitive to the S1 nuclease which are present in a supercoiled plasmid, pSVS 3.3. This plasmid contains the entire transcription unit plus 5′-and 3′-flanking regions of the rat seminal vesicle IV gene on a 3.3 kb Eco RI fragment (Harris et al., 1983). Using a cDNA probe of rat seminal vesicle secretion product IV (SVS IV) mRNA, we have demonstrated S1 nuclease-sensitive sites in the 5′-flanking and in the 3′-flanking regions of SVS IV gene. The site in the 5′-flanking region has been mapped to approximately 117 bp upstream from the CAP site. This site at — 117 bp can potentially form a cruciform structure as inferred from the presence of inverted repeats in this region (Lilley, 1981; Panayotatos and Wells, 1981). We have now shown such a structure most probably exists. The S1 nuclease-sensitive site in the 3′-flanking region is present in an area of highly repeated sequence.