ISOLATION AND CHARACTERIZATION OF THE CDNA-ENCODING THE SPINY DOGFISH SHARK (SQUALUS-ACANTHIAS) FORM OF CYTOCHROME P450C17

被引：31

作者：

TRANT, JM

机构：

[1] Department of Zoology and Physiology, Louisiana State University, Baton Rouge, Louisiana

来源：

JOURNAL OF EXPERIMENTAL ZOOLOGY | 1995年 / 272卷 / 01期

关键词：

D O I：

10.1002/jez.1402720104

中图分类号：

Q95 [动物学];

学科分类号：

071002 ;

摘要：

Cytochrome P450c17 is a key steroidogenic enzyme for the production of sex steroids in gonadal tissue and for cortisol production in adrenal tissue. This protein possesses two enzymatic activities. The 17 alpha-hydroxylase activity results in the introduction of a hydroxyl group at the 17 alpha-position. The resultant 17 alpha-hydroxylated, C21 pregnene is converted to a C19 androgen by the C17,20-lyase activity. A cDNA library was constructed from poly(A)-enriched mRNA isolated from spiny dogfish shark (Squalus acanthias) testis and ligated into EcoRI-cut lambda arms. The amplified library was screened using a bovine P450c17 cDNA probe and five positive clones were isolated. The described cDNA encompasses 23 bp of the 5'-untranslated region, a 1,527 bp open reading frame, and 414 bp of the 3'-untranslated region. A putative polyadenylation signal (AATAAA) is 18 bp from the poly(A) tail. Northern blot analysis showed a single transcript of 1.9 kb, thus indicating the isolated clone is a full-length cDNA. The deduced amino acid sequence of the shark form of P450c17 is 59% and 57% identical to the rainbow trout and chicken forms, respectively. The shark form is 43% to 46% identical to mammalian forms (rat, human, mouse, bovine, and porcine). There are large regions of extremely high identity shared among all the forms. The deduced shark 17 alpha-hydroxylase protein is 509 residues in length with a predicted weight of 57.2 kDa. Non-steroidogenic COS cells, transfected with the shark P450c17 cDNA, was capable of 17 alpha-hydroxylase and C17,20-lyase activities using both pregnenolone and progesterone as initial substrates. (C) 1995 Wiley-Liss, Inc.

引用

页码：25 / 33

页数：9

共 29 条

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