스테로이드 합성효소 중 는 progesterone을 을 거쳐 androstenedione으로 변환을 담당하는 효소이다. 양서류 난소에서 스테로이드 합성의 분자적 조절과정의 연구에 사용할 목적으로 북방산 개구리(Rana dybowskii) 난소에서 cDNA를 클로닝 하였다. 북방산 개구리 난포세포의 cDNA library 검색을 통해 분리된 약 2.5kb의 cDNA는 529개의 아미노산을 가진 단일 번역틀을 가지고 있었다. 개구리 의 아미노산 서열은 Xe

[ ] is the key enzyme mediating the conversion of progesterone to , ultimately to androstenedione during steroidogenesis. R. dybowskii's ovarian cDNA was cloned to understand the regulatory mechanism of ovarian steroidogenic pathway at the molecular level in amphibian. A 2.5kb cDNA clone encoding a single open-reading frame with a 519 deduced amino acid was isolated with the screening of ovarian cDNA library. This sequence contained the three highly conserved domains as seen in of other species. The comparison of amino acid sequence of Rana with other animal's showed relatively high identity with 76% in Xenopus, 63% in chicken, 60% in rainbow trout, and 45% in human. Phylogenic analysis also indicated that Rana gene was evolutionary well conserved among vertebrate. Northern analysis indicated that the two different sizes of transcripts with approximately 2.5 and 3.6kb were detected in ovary tissue, but not in other tissues. The expression vector of Rana clearly showed the activity converting the exogenous progesterone into in the nonsteroidogenic COS-1 cells. Therefore, Rana cDNA is very useful to investigate the molecular mechanism of the ovarian steroidogenesis in amphibian.

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