CELLULAR-ORIGIN, COMPLEMENTARY DEOXYRIBONUCLEIC-ACID AND N-TERMINAL AMINO-ACID-SEQUENCES OF HUMAN SEMINAL PROGASTRICSIN

The aspartic protease progastricsin (EC 3.4.23.3) is found in all part s of the mammalian stomach and has also been found extragastrically. I n humans and monkeys, seminal fluid usually contains high concentratio ns of progastricsin. Using immunohistochemistry and in situ hybridizat ion, we determined in this investigation the origin of seminal progast ricsin to be the epithelia of both the prostatic gland and the seminal vesicles. In addition, Northern (RNA) blotting showed the presence of a 1.8-kb transcript in both tissues. Seminal progastricsin clones fro m two human prostatic gland cDNA libraries were isolated and sequenced . The combined sequence manifested only six nucleotide differences fro m the published genomic and gastric cDNA sequence. One conservative ba se substitution was present in both libraries. N-Terminal amino acid s equencing of all 43 residues of the seminal proenzyme and the first 34 residues of the mature enzyme yielded sequences identical to those de duced from cDNAs derived from both gastric and prostatic origin. The r esults obtained indicate that gastric and seminal progastricsin are pr oducts of the same gene and that the observed molecular differences be tween the zymogen from the two sources are probably due to posttransla tional modifications.