Localization of prolyl endopeptidase mRNA in small growing follicles of porcine ovary.

Prolyl endopeptidase (EC3.4.21.26) has been considered a unique intracellular enzyme catalyzing internal peptide bond hydrolysis of Pro-X. In this study, the distribution of prolyl endopeptidase activity and its mRNA was investigated in the follicles of porcine ovary. Both follicular fluid and granulosa cell fractions from small follicles showed higher activity than those from large follicles. Molecular cloning and Northern blot analysis suggested that only one species of prolyl endopeptidase gene was expressed in the ovary. In addition, in situ hybridization study revealed that the prolyl endopeptidase mRNA expresssion was more noticeable in the granulosa cell layers of small ovarian follicles than in those of large follicles, suggesting its importance in the early stage of follicular development.