title: Bovine steroid 21-hydroxylase: regulation of biosynthesis.
abstract: A recombinant cDNA clone, PBC21-1, specific for bovine steroid 21-hydroxylase cytochrome P-450 (P-450C21) was identified in a bovine adrenocortical cDNA library, and this identity was confirmed by nucleotide sequencing which revealed significant amino acid homology (77%) with human P-450C21 cDNA. The pBC21-1 insert is 1.7 kilobases in length and includes a 1128 base pair region that encodes the C-terminal 376 amino acids of bovine P-450C21 as well as 535 base pairs of 3'-untranslated sequence. A novel feature of this insert is a 20 base pair intervening sequence near the 5' end, apparently the result of an aberrant splicing event. Northern blot analysis reveals that bovine P-450C21 is encoded by two transcripts, 2.3 and 2.0 kilobases in length which are detected in adrenal cortical RNA. Bovine liver, heart, kidney, and corpus luteum do not contain detectable P-450C21 transcripts. Regulation of P-450C21 gene expression by adrenocorticotropin was investigated with pBC21-1 and bovine adrenocortical cells in primary, monolayer culture. Treatment with ACTH or analogues of cAMP increases the steady-state levels of P-450C21 RNA in such cell cultures. In vitro transcription run-on assays suggest that this increase is, at least in part, due to the enhanced transcriptional activity of the P-450C21 gene.
mesh_terms: D000302:Adrenal Cortex / Q000201:enzymology; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002478:Cells, Cultured; D003001:Cloning, Molecular; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000235:genetics; D004247:DNA / Q000378:metabolism*; D004262:DNA Restriction Enzymes; D006801:Humans; D007700:Kinetics; D051379:Mice; D009693:Nucleic Acid Hybridization; D009928:Organ Specificity; D012313:RNA / Q000302:isolation & purification; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D013255:Steroid 21-Hydroxylase / Q000096:biosynthesis / Q000235:genetics*; D013250:Steroid Hydroxylases / Q000235:genetics*; D013552:Swine; D014158:Transcription, Genetic
chemical_list: D012313:RNA; D004247:DNA; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D013255:Steroid 21-Hydroxylase; D004262:DNA Restriction Enzymes