We have previously reported the DNA sequence of a 3.3 kb Eco R1 fragment which contains the entire transcription unit plus 5'- and 3'-flanking regions of the rat seminal vesicle IV gene (SVS IV). The 5'-flanking region of this gene contains a perfect inverted repeat at -117 bp from the CAP site. The potential for forming a true cruciform structure in this region can be demonstrated in supercoiled configuration. Therefore, by S1 nuclease digestion of the supercoiled plasmid SV3.3 (containing SVS IV) we have shown that there is an S1 nuclease sensitive site near the putative cruciform structure. We also detected an S1 nuclease-sensitive site in the 3'-flanking region of SVS IV about 800 bp from the termination site of the transcription unit. Recently we studied the S1 nuclease-sensitive and DNAase I hypersensitive sites in the chromatin of the SVS IV gene. We found that the region around -100 to -150 bp was susceptible to the S1 nuclease. DNAase I hypersensitive sites of SVS IV genes were present in seminal vesicle cells in which the gene is expressed and were absent in liver cells in which the gene is repressed. SVS IV gene is undermethylated in seminal vesicle and is highly methylated in liver. We have purified an estrogen responsive secretory protein from mouse uterus through HPLC. This protein is highly glycosylated. Two-dimensional gel electrophoresis indicated this estrogen stimulated protein has molecular weight of 70 KD with pI 6.5-6.8. Antibody against 70K protein has been raised in rabbits. We are in the process of establishing radioimmunoassay for this protein. Two times oligo-dt column purified mouse uterine mRNA from both immature and E2-stimulated animals have been prepared. With the aid of 70K antibody and poly A mRNA, we are able to isolate the cDNA clone which carry the genetic information for 70K protein from mouse uterine cDNA library.