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)

To detect nuclear protein factors which might account for a tissue-specific and inducible expression of the rat tyrosine aminotransferase (TAT) gene promoter, extracts from rat liver and spleen nuclei have been fractionated by heparin-sepharose chromatography and the fractions assayed for sequence-specific binding to the distal TAT gene promoter element (sequence between -313 and -210). Gel retardation experiments carried out in the presence or absence of Mg2+, Ca2+, or Zn2+ ions showed that there are at least two nuclear factors (A3 and A4) binding to the distal promoter element only in the presence of the chelator (20 mM EDTA). Incubation of the protein fractions with Zn2+ or Ca2+ instead of commonly used Mg2+allowed: (i) to avoid 3 2P-DNA-probe degradation by "contaminating" endogenous nucleases; and (ii) to detect another sequence-specific nuclear factor, A5. No other specific binding activities were found in the rat-liver nuclear fractions tested under these conditions. As the metal ions became inaccessible to chelation in excess of EDTA and EGTA when protein factor A5 was complexed to DNA we assumed that factor A5 is metalloprotein which requires Zn or Ca to maintain a structure of its DNA-binding domain. To identify the polypeptide possessing this domain, a protein gel blotting procedure was employed. By incubating gel blots with the 3 2P-DNA-probe in the buffer containing Zn2+, specific binding to the only polypeptide with approximate Mr 30 kDa was clearly revealed. Both gel retardation and gel blotting assays consistently showed that nuclear factor A5 is present in the liver, but not in the spleen extracts.
Mol Biol (Mosk)
PMID:[Nuclear factor A5 from the rat liver that requires a metal for specific interaction in vitro with distal element of the tyrosine aminotransferase gene promoter]. 257 11

Tissue-specific extinguisher-1 (TSE1) is a genetic locus on mouse chromosome 11 that can repress expression of several liver genes in trans. The activity of this locus is apparent in rat hepatoma microcell hybrids that retain chromosome 11 from mouse fibroblasts: such hybrids fail to accumulate particular hepatic mRNAs, including those encoding tyrosine aminotransferase (TAT) and phosphoenolpyruvate carboxykinase (PEPCK). In this report, we show that TSE1 from a TAT-, PEPCK- mouse hepatoma cell line expressing a fetal liver phenotype also induced TAT and PEPCK extinction when transferred into rat hepatoma recipients. Thus, TSE1 appears to be active in TAT-, PEPCK- cells of both hepatic and non-hepatic lineages. This suggests that TSE1 may play a role in the developmental regulation of hepatic gene expression in the liver.
Mol Biol Med 1989 Apr
PMID:Genetic activity of a trans-regulatory locus in hepatoma hybrid cells. 257

The primary structure of rat tyrosine aminotransferase (L-tyrosine:2-oxoglutarate aminotransferase; EC 2.6.1.5), a liver-specific enzyme involved in gluconeogenesis, has been deduced from the nucleotide sequence of a cloned full-length cDNA. The mRNA is 2362 nucleotides long (excluding the poly(A) tail) and codes for a polypeptide of 454 amino acids with a molecular weight of 50634. Unambiguous identification was obtained by comparison of this sequence with the amino acid sequences of several peptides obtained from the purified enzyme.
J Mol Biol 1985 Jul 20
PMID:Complete complementary DNA of rat tyrosine aminotransferase messenger RNA. Deduction of the primary structure of the enzyme. 286 82

The structural gene encoding liver-specific tyrosine aminotransferase (TAT; EC 2.6.1.5) was assigned to mouse chromosome 8 by screening a series of hybrid cell lines for retention of murine Tat-1 gene sequences by genomic Southern blotting. This assignment demonstrated that the Tat-1 structural gene was not syntenic with Tse-1, a chromosome 11-linked locus that negatively regulates TAT expression in trans (A. M. Killary and R. E. K. Fournier, Cell 38:523-534, 1984). We also showed that the fibroblast Tat-1 gene was systematically activated in hepatoma X fibroblast hybrids retaining fibroblast chromosomes 8 in the absence of chromosome 11 but was extinguished in cells retaining both fibroblast chromosomes. Thus, the TAT structural genes of both parental cell types were coordinately regulated in the intertypic hybrids, and the TAT phenotype of the cells was determined by the presence or absence of fibroblast Tse-1.
Mol Cell Biol 1985 Sep
PMID:Chromosomal assignment and trans regulation of the tyrosine aminotransferase structural gene in hepatoma hybrid cells. 287 83

Tyrosine aminotransferase (TAT, EC 2.6.1.5) from the kinetoplastid, Crithidia fasciculata, was purified over 2000 fold to electrophoretic homogeneity. The native form of the enzyme had a molecular weight of approximately 100,000, whereas under denaturing conditions it produced two polypeptides of approximately 50,000 and 48,000, respectively. Absence of a reaction with the periodic acid-Schiff stain suggested that the crithidial enzyme was not a glycoprotein. It was relatively stable and remained active over a wide range of pH and temperature. It exhibited a broad substrate specificity and was able to utilize L-tyrosine, L-tryptophan, and L-phenylalanine as amino donors. Antiserum produced against partially purified crithidial tyrosine aminotransferase failed to inhibit the enzymatic activity. The same antiserum cross-reacted with a soluble extract from Trypanosoma brucei gambiense, but not with that from normal mouse liver, confirming evolutionary conservatism between the two protozoa.
Mol Biochem Parasitol 1987 Aug
PMID:Purification and characterization of a tyrosine aminotransferase from Crithidia fasciculata. 289 Jan 1

Kinetics of tyrosine aminotransferase (TAT) mRNA synthesis in Morris rat hepatoma cell lines 7777 and 8994 after dexamethasone treatment (10(-7) M) was studied by molecular hybridization of the RNA with cloned fragments of TAT gene from rat liver cells. It was demonstrated that initiation of TAT gene transcription increased 20 minutes after glucocorticoid treatment. The level of TAT mRNA was not induced by dexamethasone in rat hepatoma cell line 8994. Actinomycin D prevented the deinduction of TAT by stabilization of TAT mRNA.
Mol Biol (Mosk)
PMID:[Regulation of the transcription of the tyrosine aminotransferase gene by glucocorticoids in Morris hepatoma 7777 and 8994 cells]. 289 90

The two independently derived hepatoma cell lines (HTC and Fu5-5) have previously been shown to display different sensitivities for the induction of tyrosine aminotransferase (TAT) enzyme activity and mRNA levels by glucocorticoids with the enzyme being half-maximally induced at approximately 7-fold higher concentrations of dexamethasone in HTC cells than in Fu5-5 cells. In the present study we investigated the induction of TAT activity by cAMP in order to see whether the difference is limited to the steroidal induction. Using the stable cAMP derivative (8-(4-chlorophenylthio)-cAMP) as an inducer, we found that a 6-fold higher cAMP concentration was needed in HTC cells to achieve the same extent of enzyme induction as in Fu5-5 cells. The induction of TAT enzyme activity could be accounted for by an increased amount of TAT mRNA. Further experiments involving sequential addition of both inducers in general showed a synergism of steroids and cAMP for TAT induction in HTC cells only at submaximal concentrations of steroid; in Fu5-5 cells, the occurrence of synergism depended on the order of addition of inducers. The maximal response in HTC cells was limited to the value that could be achieved by induction with steroid alone. In Fu5-5 cells, however, the steroid response could be augmented when cAMP was added to cells already maximally induced by steroid. This demonstrates that the effect of a combination of cAMP and steroids depends on their concentration, the sequence of their addition, and the rat hepatoma cell line used. Collectively the data suggest that a common pretranslational event determines the differential sensitivity of TAT induction by glucocorticoids and by cAMP in HTC and Fu5-5 cells. Furthermore a second, or possibly the same, common event also regulates the maximum level of TAT induction that is obtainable under most conditions with glucocorticoids and/or cAMP.
Mol Endocrinol 1987 Jan
PMID:Differential sensitivity of HTC and Fu5-5 cells for induction of tyrosine aminotransferase by 3',5'-cyclic adenosine monophosphate. 290 Oct 31

The glucocorticoid-progesterone responsive element (GRE/PRE) of the tyrosine aminotransferase (TAT) gene is a steroid-inducible enhancer. We show that the GRE/PRE can also work in the absence of a distal promoter element when located 5' to the ovalbumin TATA box. The GRE/PRE in this position retains progesterone or glucocorticoid receptor and hormone dependency for the induction of gene expression. Initiation of transcription occurs correctly, and induction occurs at the mRNA level. These data indicate that a steroid-inducible enhancer can function without a distal promoter element.
Mol Endocrinol 1988 Dec
PMID:A steroid response element can function in the absence of a distal promoter. 290 64

The enzyme tyrosine aminotransferase (TAT) is induced by unusually low concentrations of glucocorticoids in Fu5-5 cells. We have isolated clones of Fu5-5 cells infected with mouse mammary tumor virus (MMTV) in order to simultaneously compare the glucocorticoid regulation of the host cell gene, TAT, with that of another primary inducible gene, MMTV. In the two clones that were examined in detail, MMTV RNA induction occurred at 4- to 11-fold higher concentrations of dexamethasone than those needed for induction of TAT mRNA. Furthermore, the amount of agonist activity displayed by the irreversible antiglucocorticoid dexamethasone 21-mesylate was greater for the induction of TAT mRNA than for MMTV RNA. These results extend our previous observations of unequal sensitivity of induction of TAT enzyme activity in two hepatoma cell lines and show that differential glucocorticoid regulation of gene induction within the same cell can occur at a pretranslational step. The present data also indicate that the unusual properties of TAT gene induction are not shared by all primary, glucocorticoid-inducible responses of the same cell and imply that additional factors mediating differential regulation of glucocorticoid-responsive genes are involved.
Mol Endocrinol 1988 Nov
PMID:Unlinked regulation of the sensitivity of primary glucocorticoid-inducible responses in mouse mammary tumor virus infected Fu5-5 rat hepatoma cells. 290 13

1. The response of tyrosine aminotransferase activity in isolated liver cells has been studied under several conditions. 2. Activity is increased over a 5 h period by both glucagon and glucocorticoids in cells from adrenalectomized rats. The results do not support the view that glucagon action is dependent on preexposure of cells to steroid. 3. In cells from fed animals, significant stimulation is seen only when both glucagon and steroid are present together. 4. In cells from 48 h fasted rats steroid is effective, but glucagon is not significant so. 5. These anomalies are attributed to the differences in hormonal and nutritional status between the animals from which the cells are isolated.
Mol Cell Biochem 1981 Jan 20
PMID:Factors affecting induction of tyrosine aminotransferase in isolated rat liver cells. 611 64


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