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

The human prostate tumor cell line LNCaP contains an abnormal androgen receptor system with broad steroid binding specificity. Progestagens, estradiol and several antiandrogens compete with androgens for binding to the androgen receptor in the cells to a higher extent than in other androgen sensitive systems. Optimal growth of LNCaP cells is observed after addition of the synthetic androgen R1881 (0.1 nM). In addition, estrogens, progestagens and several antiandrogens do not inhibit androgen responsive growth, but have striking growth stimulatory effects and increase EGF receptor level and acid phosphatase secretion. We have found that the androgen receptor in the LNCaP cells contains a single point mutation changing the sense of codon 868 (Thr to Ala) in the ligand binding domain. Expression vectors containing the normal or mutated androgen receptor sequence were transfected into COS or HeLa cells. Androgens, progestagens, estrogens and several antiandrogens bind the mutated androgen receptor protein and activate the expression of an androgen-regulated reporter gene (GRE-tk-CAT), indicating that the mutation directly affects both binding specificity and the induction of gene expression. Interestingly, the antiandrogen casodex showed antiandrogenic properties in growth studies of LNCaP cells and did not induce reporter gene activity in Hela cells transfected with the mutant receptor. The mutated androgen receptor of LNCaP cells is therefore a useful tool in the elucidation of different levels of action of steroids and antisteroids.
J Steroid Biochem Mol Biol 1992 Mar
PMID:The androgen receptor in LNCaP cells contains a mutation in the ligand binding domain which affects steroid binding characteristics and response to antiandrogens. 156 39

A series of human androgen receptor (AR) deletion mutants was constructed to study the relationship between various structural domains and their different functions in the AR protein. Immunoblots of wild type AR and AR mutants expressed in COS-1 cells, revealed a doublet appearance of all AR proteins. One exception was an AR mutant lacking amino acid residues 51-211 that migrated as a single protein band, possibly due to altered post-translational modification. The steroid binding domain was found to be encoded by approx. 250 amino acid residues in the C-terminal end. Deletions and truncations in this part of the receptor abolished hormone binding. The N-terminal domain was observed to be essential for transcriptional activation. AR mutants lacking large parts of this domain were transcriptionally inactive. Deletion of the hormone binding domain yielded a constitutively active AR protein, indicating that in the absence of hormone this domain displays an inhibitory function. In the absence of ligand the wild type AR expressed in COS-1 cells was distributed over nucleus and cytoplasm. The addition of hormone directed all androgen receptors to the nucleus. In contrast, an AR mutant lacking part of the DNA binding domain and part of the hinge region, was almost exclusively cytoplasmic in the absence of hormone. This mutant lacks a conserved region, homologous to the SV40 large T- and nucleoplasmin nuclear localization signal. Hormone induced transfer of this AR mutant to the nucleus, indicating the presence of a second, hormone dependent nuclear targeting mechanism.
J Steroid Biochem Mol Biol 1992 Mar
PMID:Functional domains of the human androgen receptor. 156 40

Two molecular species of bovine P450(11 beta), P450(11 beta)-2 and P450(11 beta)-3 have been identified, in which the amino acid differences were found at the 6th, 36th and 82nd positions from the NH2-termini of the mature proteins. They catalyzed the 11 beta-, 18- and 19-hydroxylation and aldosterone formation from 11-deoxycorticosterone, and the rate of production of 18-hydroxycorticosterone and aldosterone by P450(11 beta)-3 was greater than that by P450(11 beta)-2 [Morohashi et al., J. Biochem. 107 (1990) 635-640]. In this study, chimeric clones were constructed whose 6th, 36th and 82nd amino acid residues were exchanged with each other. Two original clones and six chimeric clones were expressed in COS-7 cells, and their steroidogenic activities studied. The ratio of aldosterone or 18-hydroxycorticosterone production to corticosterone production by one clone was compared with that of the other. The ratios for the four clones having Gly36 [P450(11 beta)-3 type] were 0.08-0.22, whereas those for the clones having Ser36 [P450(11 beta)-2 type] were 0.03-0.05, suggesting that the Gly36 structure is important for aldosterone production.
J Steroid Biochem Mol Biol 1992 Mar
PMID:Functional expression of cDNAs for bovine 11 beta-hydroxylase-aldosterone synthases, P450(11 beta)-2 and -3 and their chimeras. 156 54

A novel adenosine receptor subtype has been cloned from a rat brain cDNA library using a probe generated by the polymerase chain reaction. The cDNA, designated RFL9, encodes a protein of 332 amino acids. The structure of RFL9 is most similar to that of the recently cloned rat A2-adenosine receptor, with a sequence identity of 73% within the presumed seven transmembrane domains. Expression of RFL9 in COS-6M cells resulted in ligand binding and functional activity characteristics of an adenosine receptor that is coupled positively to adenylyl cyclase. Examination of the tissue distribution of RFL9 mRNA by Northern blot analysis showed a restricted distribution with highest levels expressed in large intestine, cecum, and urinary bladder; this pattern was distinct from that of either the A1- or A2-adenosine receptor mRNAs. In situ hybridization studies of RFL9 mRNA showed no specific hybridization pattern in brain, but a hybridization signal was readily observed in the hypophyseal pars tuberalis. Thus, RFL9 encodes a novel A2-adenosine receptor subtype.
Mol Endocrinol 1992 Mar
PMID:Molecular cloning and expression of the cDNA for a novel A2-adenosine receptor subtype. 158 14

The T4-binding globulin-Gary (TBG-G) variant has severely impaired T4 binding, is unstable at 37 C, and presents an apparent anodal shift of all isoforms when submitted to isoelectric focusing. Inheritance of this abnormal TBG produces a profound decrease in the serum levels of native TBG with reciprocal changes in its denatured form, causing thyroid hormone concentrations to be as low as those found in complete TBG deficiency. The TBG-G gene possesses a single nucleotide substitution replacing the normal IIe96 (ATC) with Asn (AAC), thus creating a new site for N-linked glycosylation. In order to determine whether TBG-G contains an additional carbohydrate chain as indirectly suggested by the isoelectric focusing results, cDNAs containing the normal TBG (TBG-N), and TBG-G were inserted in the appropriate vectors to allow their expression in mammalian cells (COS-1) and in amphibian (Xenopus) oocytes. In both systems, expression of TBG-G yielded a larger molecule than TBG-N when analyzed by polyacrylamide gel electrophoresis under denaturing conditions. However, both were identical in size when synthesized in COS-1 cells in the presence of tunicamycin or when deglycosylated after their synthesis in Xenopus oocytes. Pulse chase experiments revealed impaired secretion and excessive overall intracellular degradation of TBG-G relative to TBG-N. As expected from studies on serum from affected subjects, in vitro expressed TBG-G had a 10-fold lower affinity for T4. These studies prove that the new site for potential glycosylation created by the point mutation in TBG-G is indeed glycosylated.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Endocrinol 1992 Mar
PMID:An additional carbohydrate chain in the variant thyroxine-binding globulin-Gary (TBGAsn-96) impairs its secretion. 158 18

cDNAs coding for the heavy and light chains of a bovine anti-testosterone IgG1 monoclonal antibody have been cloned and sequenced. These cDNAs are the first to be reported for functionally rearranged bovine immunoglobulin genes. Testosterone binding by the antibody encoded by the cDNAs has been verified by expression of the cDNAs in COS-1 cells and detection of anti-testosterone antibodies in transfected cell media using an ELISA specific for bovine anti-testosterone IgG. The derived protein sequence of the variable domains have suggested a possible binding model for the interaction between the antibody and testosterone. The derived protein sequence of the constant domains has been used to identify residues which could be involved in the selective transport of bovine IgG1 from blood plasma into colostrum at the time of parturition.
Mol Immunol 1992 May
PMID:Nucleotide sequences and expression of cDNAs for a bovine anti-testosterone monoclonal IgG1 antibody. 158 33

DNA binding domain proteins (DBDP) were prepared using a pET construct containing an insert coding for amino acids 49-122 of human thyroid hormone receptor (hTR) alpha and 103-179 of hTR beta. These proteins were expressed in Escherichia coli strain BL21 (DE3)-plysS after induction by isopropyl-D-thiogalactopyranoside (IPTG). The hTR alpha and hTR beta DBDP contain respectively 79 and 82 amino acids, including an amino terminal 4 amino acid extension derived from pET-3a or the synthesized initiation codon. Using a gel shift assay, both DBDPs were found to bind to a DNA oligonucleotide containing a thyroid hormone response element (TRE). The DBDPs competed with full length hTR alpha 1 for binding to the oligonucleotide. Apo-DBDPs (Zn2+ released by low pH) failed to bind to the palindromic TRE. DNA binding is restored however if apo-DBDP is preincubated in 500 microM Zn2+. When the DBDPs were expressed in COS-7 cells using a pCB6+ expression vector, they did not induce expression of a TRE-CAT fusion gene. hTR DBDPs thus can bind to DNA, presumably as monomers, since they do not contain the leucine zipper-like motif for dimerization. In COS-7 cells, they fail to cause transactivation of a TRE-CAT fusion gene. It is inferred that this may be because the DBDPs are not translocated to the nucleus or lack a transactivation domain.
Mol Cell Endocrinol 1992 Apr
PMID:Expression and function of a human thyroid hormone receptor-derived DNA-binding domain protein. 158 92

Sulfation is an important pathway in the metabolism of many hormones and drugs. Human liver contains at least three well characterized sulfotransferase (ST) enzymes, i.e., dehydroepiandrosterone (DHEA) ST and two forms of phenol sulfotransferase (PST). Our goal was to purify, to obtain partial amino acid sequence for, and to clone and express cDNA for human liver DHEA ST. Polymerase chain reaction primers were designed on the basis of homology among rat liver hydroxysteroid ST, rat liver PST, and bovine estrogen ST. These primers amplified a unique sequence from human liver cDNA, and this polymerase chain reaction product was used to screen a human liver cDNA library. Two clones were isolated that contained identical open reading frames, of 855 nucleotides, that encoded a protein of 285 amino acids. The deduced amino acid sequence of the encoded protein included two separate 27- and 23-amino acid sequences that were identical to those obtained by microsequencing of proteolytic fragments from purified human liver DHEA ST. Translation, in a rabbit reticulocyte lysate system, of mRNA transcribed in vitro from the two cDNA clones resulted in a 35-kDa translation product that comigrated with purified human liver DHEA ST during sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This translation product also catalyzed the sulfation of DHEA but not the sulfation of model substrates for the two forms of PST found in human liver. The two cDNA clones were also used to create expression constructs with the eukaryotic expression vector P91023(B), and these constructs were used to transfect COS-1 cells. The transfected cells expressed a high level of DHEA ST activity, and this enzyme activity displayed a pattern of inhibition by the ST inhibitor 2,6-dichloro-4-nitrophenol identical to that of human liver DHEA ST. Cloning of cDNA for this important human sulfate-conjugating enzyme will enhance understanding of the relationship between DHEA ST and other human liver STs, as well as ST enzymes in other species.
Mol Pharmacol 1992 May
PMID:Human liver dehydroepiandrosterone sulfotransferase: molecular cloning and expression of cDNA. 158 21

To determine the biological role, if any, of the NH2-terminal region of beta-1,4-galactosyltransferase (GT; EC 2.4.1.90), we constructed deletion mutants and expressed them in COS-7 cells. Each deletion construct was analyzed for enzymatic activity, protein production and mRNA transcription. All of the deletion mutants were transcribed to produce GT mRNA, but the GT protein was not detected in those constructs whose transmembrane (aa 14-42) domain was deleted. The results suggest that the transmembrane region is essential for the stability of the protein and perhaps contain sequences critical for the proper targeting of the molecule. The possible role of the NH2-terminal signal anchor domain in the in vivo regulation of GT is discussed.
Mol Biol Rep 1992 May
PMID:Deletion analysis of the NH2-terminal region of beta-1,4-galactosyltransferase. 160 3

5-Lipoxygenase-activating protein (FLAP) is specifically labeled by [125I]L-669,083 and [125I]L-691,678, photoaffinity analogues of two classes of potent leukotriene biosynthesis inhibitors. Because human FLAP contains only a single tryptophan residue at position 72 and two internal methionine residues at positions 89 and 125, we have used reagents that specifically cleave at these residues, in conjunction with antipeptide antisera, to localize the site of attachment of the photoaffinity ligands. Immunoprecipitation of specifically labeled peptide fragments after digestion of photoaffinity-labeled FLAP by iodosobenzoic acid at 72Trp demonstrates that the inhibitors bind to FLAP amino-terminal to this residue. This finding is consistent with similar immunoprecipitation studies after digestion at methionine residues using cyanogen bromide. These findings localize the site of attachment of the inhibitors to a region of FLAP that includes the hydrophilic loop between the proposed first and second transmembrane regions. Based on these findings, site-directed mutagenesis of human FLAP was performed to define key amino acids involved in inhibitor binding. Using a radioligand binding assay, analysis of mutants of human FLAP expressed in COS-7 cells demonstrates that a number of residues in the amino-terminal half of the first hydrophilic loop of the protein can be deleted without significantly affecting inhibitor binding. In contrast, no inhibitor binding was detectable with mutants in which amino acid residues in the carboxyl-terminal half of this loop were deleted. Furthermore, a point mutation of 62Asp to asparagine results in a mutant with dramatically reduced affinity for inhibitors. This loss of affinity was not displayed by a mutant in which 62Asp was mutated to a glutamate residue, suggesting that a negative charge associated with residue 62 may be critical for inhibitor binding. The roles that amino acid residues in the carboxyl-terminal half of the first hydrophilic loop of FLAP may play in the binding of leukotriene biosynthesis inhibitors are currently under investigation.
Mol Pharmacol 1992 Jul
PMID:Identification of amino acid residues of 5-lipoxygenase-activating protein essential for the binding of leukotriene biosynthesis inhibitors. 163 56


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