Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The molecular pathology of steroid 21-hydroxylase deficiency is attributable to unequal crossover-mediated gene deletion or to large- or small-scale replacement of the functional CYP21B gene sequence by a copy of the analogous CYP21A pseudogene sequence. Because the pathological point mutations originate from the pseudogene which shows only a small number of differences from the functional CYP21B gene sequence, the total number of different pathological point mutations is likely to be small. Mutant P450c21 enzymes carrying specific amino acid substitutions seen in patients with 21-hydroxylase deficiency exhibit activities that correlate with the clinical severity of the disease and with biochemical abnormalities such as 17-hydroxyprogesterone levels after ACTH (corticotropin) stimulation.
J Steroid Biochem Mol Biol 1991
PMID:Molecular pathology of steroid 21-hydroxylase deficiency. 195 56

A point mutation within exon 7 producing an amino acid coding change and a recognition site for the endonuclease Ncol has been reported in the HLA-Bw47-linked CYP21A pseudogene and some mutant CYP21B (steroid 21-hydroxylase) genes of patients with congenital adrenal hyperplasia (CAH). Whether this mutation is deleterious was not demonstrated. We analyzed DNA from various subjects for the presence of the exon 7 Ncol site: group 1, 10 normal subjects; group 2, 11 patients with salt-losing CAH; and group 3, 18 members of an Amish pedigree in which 10 expressed HLA-Bw47 not linked to CAH. Southern blots of Ncol-digested genomic DNA which were hybridized with CYP21 cDNA showed that four subjects of group 1 had a heterozygous Ncol pattern. In group 2, seven patients had the Ncol site; two of them were homozygous for the site and had deletions of both CYP21B genes. The other five were heterozygous for the Ncol site, which was linked to a CYP21B deletion and a HLA-Bw47 haplotype. In group 3, no one exhibited the exon 7 Ncol site. To map the Ncol sites to CYP21A or CYP21B in the normal subjects, DNA from the four Ncol heterozygous subjects was double digested with Ncol and Mbol and hybridized with CYP21 cDNA. Ncol-Mbol fragments unique to CYP21A were identified in all four, but the smaller CYP21B-specific fragments were not detected. Their genomic DNA in the region of exon 7 (bases +1167 to +2058) was then amplified, cloned, and sequenced.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Endocrinol 1990 Sep
PMID:Exon 7 Ncol restriction site within CYP21B (steroid 21-hydroxylase) is a normal polymorphism. 197 47

Steroid 21-hydroxylase activity of the microsome-enriched fraction of follicular linings from equine ovaries has been demonstrated by gas chromatography-mass spectrometry. The 21-hydroxylated metabolites were quantified by isotope dilution with deuterated analogues. The two most abundant potential substrates for follicular steroid 21-hydroxylase, progesterone (P) and 17-hydroxyprogesterone (17OHP), were converted respectively to 11-deoxycorticosterone (DOC) and 11-deoxycortisol with corresponding apparent specific activities of 308 and 24 pmol/mg protein/h and apparent Km values of 1.1 and 6.4 microM. Competitive inhibition of the P-to-DOC conversion was exerted by 17OHP and pregnenolone. Hence, the ovarian follicle of the mare is an extraadrenal site of preferential DOC biosynthesis by an enzyme having steroid 21-hydroxylase activity.
J Steroid Biochem Mol Biol 1991 Feb
PMID:Steroid 21-hydroxylase activity in equine ovarian follicles evidenced by isotope dilution-mass spectrometry. 200 39

The mild nonclassic form of steroid 21-hydroxylase deficiency is one of the most common autosomal recessive disorders in humans, occurring in almost 1% of caucasians and about 3% of Ashkenazi Jews. Many patients with this disorder carry a Val-281----Leu missense mutation in the CYP21 gene. This and most other mutations causing 21-hydroxylase deficiency are normally present in the CYP21P pseudogene and have presumably been transferred to CYP21 by gene conversion. To identify other potential nonclassic alleles, we used recombinant vaccinia virus to express two mutant enzymes carrying the mutations Pro-30----Leu (normally present in CYP21P) and Ser-268----Thr (considered a normal polymorphism of CYP21). Whereas the activity of the protein carrying the Ser----Thr mutation was indeed indistinguishable from the wild type, the enzyme with the Pro----Leu substitution had 60% of wild-type activity for 17-hydroxyprogesterone and about 30% of normal activity for progesterone when assayed in intact cells. When kinetic analysis of the latter mutant enzyme was performed in cellular lysates, the first order rate constants (maximum velocity/dissociation constant) for both substrates were reduced 10- to 20-fold compared with those for the wild-type enzyme. Pro-30 is conserved in many microsomal P450 enzymes and may be important for proper orientation of the enzyme with respect to the aminoterminal transmembrane segment. The Pro----Leu mutation was present in 5 of 18 patients with nonclassic 21-hydroxylase deficiency, suggesting that this mutation indeed acts as a nonclassic deficiency allele.
Mol Endocrinol 1991 May
PMID:A mutation (Pro-30 to Leu) in CYP21 represents a potential nonclassic steroid 21-hydroxylase deficiency allele. 207 28

The changes in steady-state levels of mRNA for cholesterol side-chain cleavage cytochrome P-450 (P-450scc) and steroid 21-hydroxylase cytochrome P-450 (P-450c21) caused by hypophysectomy and ACTH treatment were determined in rat adrenals. Hypophysectomy caused marked decreases in adrenal weight and total RNA per gland. Administration of ACTH resulted in increases in adrenal weight and total RNA. A significant correlation between the amount of RNA and adrenal weight was observed. Both P-450scc and P-450c21 mRNAs were decreased by hypophysectomy and increased by ACTH treatment. P-450scc mRNA decreased to 20% and P-450c21 mRNA to 76% of control values 1 day after hypophysectomy. ACTH caused a significant increase in P-450scc mRNA after 3 h. However, a significant increase in P-450c21 mRNA was observed 12 h after administration of ACTH. These results are concordant with previous studies in vitro utilizing cultured adrenocortical cells. Moreover, the induction of steady-state levels of P-450scc mRNA was faster than that observed by other investigators in studies in vitro. These results may indicate that integrity of the adrenal gland in vivo is important for the action of ACTH.
J Mol Endocrinol 1990 Jun
PMID:Alteration in the expression of genes for cholesterol side-chain cleavage enzyme and 21-hydroxylase by hypophysectomy and ACTH administration in the rat adrenal. 216 81

Cytochrome P450c21 (steroid 21-hydroxylase) is a key enzyme in the synthesis of cortisol, whose deficiency is the cause of a common genetic disease, congenital adrenal hyperplasia. We have expressed P450c21 (steroid 21-hydroxylase) in E. coli and mammalian cells. In E. coli, P450c21 cDNA was cloned into a T7 expression vector to produce a large amount of P450c21 fusion protein, which enabled antiserum production. In mammalian cells, a plasmid containing full-length P450c21 cDNA (phc21) was constructed and transfected into COS-1 cells to produce active P450c21, which was detected by immunoblotting and 21-hydroxylase activity assay. This system was used to assay mutations involved in the disease. Ile172 of phc21 corresponding to the site of mutation in some cases of the disease was mutagenized to become Asn, Leu, His, or Gln. Mutant as well as normal P450c21 was produced when their cDNAs were transfected into COS-1 cells. The mutant proteins, however, had greatly reduced 21-hydroxylase activities. Therefore, missense mutation at Ile172 resulted in inactivation of the enzyme, but not in repression of enzyme synthesis. The Leu for Ile substitution at amino acid 172 did not result in partial restoration of enzymatic activity, indicating that hydrophobicity at this residue may not play a role in its function.
Mol Endocrinol 1990 Jun
PMID:Expression of human 21-hydroxylase (P450c21) in bacterial and mammalian cells: a system to characterize normal and mutant enzymes. 223 46

Cortisol production from cholesterol requires the activity of four steroid hydroxylases: cholesterol side chain cleavage cytochrome P-450 (P-450scc), 17 alpha-hydroxylase cytochrome P-450 (P-45017 alpha), 21-hydroxylase cytochrome P-450 (P-450C21) and 11 beta-hydroxylase cytochrome P-450 (P-45011 beta). We have previously shown that transformed, nonsteroidogenic COS 1 cells derived from monkey kidney are a useful system for expression of various forms of cytochrome P-450. The present study shows that COS 1 cell cultures multiply transfected with six plasmids containing all four steroid hydroxylases, 3 beta-hydroxysteroid dehydrogenase/delta 5----4-isomerase (3 beta HSD) and adrenodoxin produce cortisol and aldosterone when 22(R)-hydroxycholesterol is supplied to the system. When pregnenolone is used as substrate, various intermediate metabolites are detected at different time points further establishing the incorporation of complete functional steroidogenic pathways into the nonsteroidogenic cell cultures. Since the first and the last reactions in these pathways take place in the mitochondrion, the movement of various intermediate metabolites from mitochondrion to endoplasmic reticulum and back to mitochondrion occurs in and between COS 1 cells.
Mol Cell Endocrinol 1990 Oct 01
PMID:Incorporation of steroidogenic pathways which produce cortisol and aldosterone from cholesterol into nonsteroidogenic cells. 229 41

Congenital adrenal hyperplasia (CAH) is a family of inherited disorders of adrenal steroidogenesis, most commonly due to deficiency of P-450 21-hydroxylase (21-OH). There are two genes for 21-OH on the short arm of chromosome 6, the A gene which is thought to be inactive, and the B gene. These genes appear as 3.2 and 3.7 kb TaqI fragments on Southern blots. In a study of DNA from 60 normal controls with TaqI and a 21-OH cDNA probe, 12% exhibited a homozygous deletion of the A gene, and 22 and 8% heterozygous deletions of A and B genes respectively. TaqI analysis of eight patients with CAH revealed four without A or B gene deletions, three with heterozygous deletions of the B gene and one with a homozygous deletion of the B gene. On further analysis with KpnI, EcoRI, PvuII and BglII, however, these genotypes were amended to two with heterozygous deletions of the B gene and two with possible B to A gene conversions. The genotypes of the four patients without deletions remained unchanged. RNA from CAH and Cushing's adrenal tissue was also analysed using A and B gene-specific oligodeoxynucleotide probes. B gene transcripts were detected in both CAH and Cushing's adrenals, while no A gene transcripts could be detected in either tissue. The level of B gene-derived mRNA was greater in the Cushing's adrenal than in the CAH adrenal, which in turn was greater than that in the adrenal from a normal individual.(ABSTRACT TRUNCATED AT 250 WORDS)
J Mol Endocrinol 1988 Nov
PMID:DNA and RNA analysis of cytochrome P-450 21-hydroxylase: transcriptional activity in congenital adrenal hyperplasia. 247 27

The selective inactivation by 17 beta-substituted steroids of rabbit and rat liver cytochromes P-450 involved in the 21-hydroxylation of progesterone has been investigated. Five derivatives each of pregnenolone and progesterone were prepared, in which the methylketo substituent of the 17 beta-position was replaced by a dichloromethylketo, chlorofluoromethylketo, difluoromethylketo, vinyl, or ethynyl group. The ability of the compounds to cause time-dependent (inactivation) and time-independent (inhibition) decreases in progesterone hydroxylase activity was assessed in vitro using intact liver microsomes as well as reconstituted systems containing the major forms of hepatic cytochrome P-450 responsible for progesterone 21-hydroxylation, P-450 1 in the rabbit and PB-C in the rat. In each species, one compound was identified that specifically inactivated the 21-hydroxylase, namely 21-chloro-21-fluoropregnenolone in the rabbit and pregn-4,20-diene-3-one in the rat, although both compounds inhibited several other hydroxylases as well. Moreover, the most effective and specific 21-hydroxylase inactivators were not necessarily the most effective or specific inhibitors. These results suggest that conversion of the enzyme-inhibitor complex to metabolites that inactivate the enzyme, rather than complex formation, is the crucial factor in determining the specificity of the compounds as cytochrome P-450 inactivators. The results indicate the feasibility of designing specific inactivators of hepatic cytochromes P-450 by utilizing the normal regioselectivity of the target enzyme towards steroids.
Mol Pharmacol 1989 Jan
PMID:Specific inactivation by 17 beta-substituted steroids of rabbit and rat liver cytochromes P-450 responsible for progesterone 21-hydroxylation. 278 20

The amino acid sequences of two steroidogenic enzymes, P450c17 (steroid 17 alpha-hydroxylase/17,20 lyse) and P450c21 (steroid 21-hydroxylase), are only 28.9% identical. However, these proteins share a region of 21 amino acids bearing 17 identical residues, which we previously suggested may represent the steroid binding site. We assembled a sequence database of known steroid-binding proteins and searched this with the sequence of this 21 amino acid region. The steroidogenic enzymes, P450c17, P450c21, P450scc (the cholesterol side-chain cleavage enzyme), and P450c11 (steroid 11 beta/18-hydroxylase) share a subregion of 17 amino acids having at least 15 identical residues. Related sequences were identified in a computerized search of the available sequences of steroid hormone receptors and binding proteins. These sequences were invariably found within larger domains previously associated with steroid binding. From these we propose a more general consensus sequence of LPLLL +/- 000KDRE0LKRL +/- PV, where +/- refers to any charged amino acid, and 0 refers to an uncharged amino acid. This consensus sequence predicts 147 or 187 total amino acids in 11 human proteins examined (78.6%). An equivalent degree of sequence identity, 178 of 221 amino acids (80.5%) was found among 13 animal homologs of these human proteins. The ability of this consensus sequence to predict 325 of 408 amino acids (79.7%) strongly suggests this sequence is necessary, if not sufficient, for a steroid binding site in many proteins. Lecithin-cholesterol acetyl transferase, cholesterol ester transfer protein, and steroid sulfatase did not have sequences similar to our consensus sequence.
Mol Endocrinol 1988 Nov
PMID:Homologous sequences in steroidogenic enzymes, steroid receptors and a steroid binding protein suggest a consensus steroid-binding sequence. 326 73


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>