20beta-Hydroxysteroid dehydrogenase of the Japanese eel ovary: its cellular localization and changes in the enzymatic activity during sexual maturation.
In many species of teleost, 20beta-hydroxysteroid dehydrogenase (20beta-HSD) is a key steroidogenic enzyme in the production of the oocyte maturation-inducing steroid (MIS), 17alpha, 20beta-dihydroxy-4-pregnen-3-one. In this study, 20beta-HSD in the ovary of the Japanese eel was biochemically characterized using a cell-free system. 20beta-HSD activity was located mainly in the membrane-bound fractions of the mitochondria and microsome, with lower levels detected in the cytosolic fraction. The enzymatic activity of membrane-bound 20beta-HSD was strikingly enhanced by treatment of eels with gonadotropin-rich salmon pituitary homogenate. The activity of eel ovarian mitochondrial 20beta-HSD in the presence of different solubilizing detergents was then assessed. Mitochondrial fractions solubilized by sodium deoxycholate and octhylthioglucoside retained approximately 30% of 20beta-HSD activity when compared to those of nontreated mitochondria. These results suggest that Japanese eel ovarian 20beta-HSD is composed of membrane-bound and soluble activities, and that the membrane-bound component is stimulated by gonadotropin.
Kazeto
Y
Y
Division of Marine Biosciences, Graduate School of Fisheries Science, Hokkaido University, 3-1-1 minato-cho, Hakodate, Hokkaido, 041-8611, Japan. kazeto@umbi.umd.edu
Adachi
S
S
Yamauchi
K
K
D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D003349:Cortisone Reductase / Q000032:analysis / Q000378:metabolism*; D003600:Cytosol / Q000201:enzymology; D003902:Detergents / Q000494:pharmacology; D004524:Eels / Q000254:growth & development / Q000378:metabolism*; D005260:Female; D006065:Gonadotropins, Pituitary / Q000494:pharmacology; D006908:Hydroxyprogesterones / Q000494:pharmacology; D008861:Microsomes / Q000201:enzymology; D008928:Mitochondria / Q000201:enzymology; D010053:Ovary / Q000201:enzymology* / Q000254:growth & development / Q000648:ultrastructure; D012741:Sexual Maturation; D013045:Species Specificity
D003902:Detergents; D006065:Gonadotropins, Pituitary; D006908:Hydroxyprogesterones; C021012:17 alpha,20 beta-dihydroxypregn-4-en-3-one; D003349:Cortisone Reductase