Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

P-450c21, a cytochrome P-450 enzyme [steroid 21-monooxygenase (steroid 21-hydroxylase), EC 1.14.99.10], mediates the 21-hydroxylation of glucocorticoid and mineralocorticoid hormones in the adrenal gland. The complete sequence of a bovine P-450c21 gene shows it is 3447 base pairs long and contains 10 exons. The intron/exon organization and encoded amino acid sequence indicate that P-450c21 represents a unique family of genes in the P-450 gene superfamily. Primer extension and S1 nuclease protection experiments identified several cap sites for initiation of transcription; the principal cap site produces mRNA with a 5' untranslated region only 11 bases long. S1 nuclease protection experiments confirm that P-450c21 is actively expressed in the adrenal and the testis, an organ not known to secrete 21-hydroxylated steroids.
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PMID:Structure of a bovine gene for P-450c21 (steroid 21-hydroxylase) defines a novel cytochrome P-450 gene family. 348 86

Steroid 21-hydroxylase is expressed at high levels in the adrenal gland, where it is required for the synthesis of mineralocorticoids and glucocorticoids. The cis-acting nucleotide sequences required for expression of murine 21-hydroxylase were assessed by stable transfection of Y1 adrenocortical tumor cells with 21-hydroxylase genes containing progressive deletions of the 5' flanking sequences. Expression of authentic 21-hydroxylase transcripts was quantitated by S1 nuclease protection assays using total RNA from pools of transfectant colonies. Removal of sequences from 1,100 to 230 base pairs preceding the transcription initiation site did not significantly affect 21-hydroxylase transcription. However, an important regulatory element falls between 230 and 180 base pairs upstream of the transcription initiation site. Comparisons of the murine 5' flanking sequence with those of the human and bovine 21-hydroxylase genes revealed a 40-base pair region that is highly conserved among all three species. The conserved sequence in the murine gene occurs between 210 and 170 nucleotides 5' of the transcription initiation site; similar locations are seen in the human and bovine genes. These results thus define an important regulatory region which is required for expression of 21-hydroxylase in Y1 adrenal cells.
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PMID:Characterization of a regulatory region of the steroid 21-hydroxylase gene. 349 Oct 69

P450c17 is a single cytochrome P450 enzyme mediating both 17 alpha-hydroxylase and 17,20 lyase activities in the biosynthesis of steroid hormones. We have cloned and sequenced the human P450XVIIA1 gene lying on chromosome 10, which encodes P450c17. The gene spans 6569 bp and is divided into eight exons by seven introns. This intron/exon structure closely resembles that of the P450XXI genes encoding P450c21 (steroid 21-hydroxylase), which contain 10 exons, except that the introns dividing exons 1 and 2 and exons 4 and 5 in the P450XXI gene are absent in the P450XVII gene. Furthermore, computer modeling studies indicate the conformations of P450c17 and P450c21 are very similar. The structures of the P450XXVII and P450XXI genes are very different from other classes of P450 genes. Although the production of P450c17 is under different hormonal, ontogenic, and tissue-specific controls in various types of steroidogenic cells, the adrenal and testis transcribe the P450XVIIA1 gene into P450c17 mRNAs having the same cap sites. S1 nuclease protection experiments locate the principal cap sites as a G residue lying 22 bases 3' to an atypical TTTAAA promoter, and 82 bases 3' to a typical CAAT box. The 5'-flanking DNA contains sequences similar to consensus sequences regulated by cAMP and glucocorticoids.
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PMID:Cloning and sequence of the human gene for P450c17 (steroid 17 alpha-hydroxylase/17,20 lyase): similarity with the gene for P450c21. 350 22