Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.108 (TAT)
 2,389 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Changes in liver tyrosine aminotransferase induction were measured in mice after repeated or prolonged stressing. In the repeated chloroform stress variant the first impulse determines the amplitude of TAT induction; the second stress can only produce superinduction if repeated 40 minutes after the onset of the first one. In the prolonged irradiation stress variant the response was dependent on both the dose rate and duration of irradiation.
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PMID:Liver enzymatic induction after repeated or prolonged stress. 0 91

L-Tyrosine:2-oxoglutarate aminotransferase (EC 2.6.1.5; TAT) and other enzymes that transaminate tyrosine in rat liver cytosol have been separated into four fractions by isoelectric focussing. One of the forms is probably identical to mitochondrial L-aspartate:2-oxoglutarate aminotransferase (EC 2.6.1.1.; mASAT). The other three forms have pI's of 4.72, 4.98 and 5.30 and Km values of 1.3 and 0.3 mM for tyrosine and alpha-ketoglutarate. These heat stable forms have little or no ASAT activity. Rat liver TAT is also separated into three peaks by hydroxylapatite. Each fraction gives only one peak of activity when electrofocussed separately. In the frog, three groups of peaks of TAT activity have been separated by hydroxylapatite column chromatography. The first group is connected with ASAT activity. These peaks (pI's 6.35, 6.50 and 6.90) are heat stable and have a Km value for tyrosine of 4 mM. These fractions probably represent cytoplasmic ASAT (sASAT). The second group of peaks has at least two subforms (pI's 9.0 and 9.4, Km for tyrosine 15 mM). These forms probably represent mASAT. The third group consists of three forms that resemble the major forms of rat liver TAT. These results indicate that heterogeneity is common to many aminotransferases and independent of regulation by glucocorticoids.
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PMID:Heterogeneity of hepatic tyrosine aminotransferase. Separation of the multiple forms from rat and frog liver by isoelectric focussing and hydroxylapatite column chromatography and their partial characterization. 0 12

Whereas glucocorticoids induce TAT, TRP, GPT in liver and only TAT in HTC cells, no hormonal effect on the synthesis of these enzymes was found in Zajdela hepatoma cells grown in vivo as an ascitic tumor, or in vitro as layer cultures. Although these cells remain uninducible, the hormone penetrates normally, but a strong decrease of the specific binding of cytosol and nuclear proteins with the hormone was observed. The impairment at the level of the hormone receptors could account for the non-inducibility of enzyme synthesis in ZHC cells.
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PMID:Impairment of enzyme induction by glucocorticoids in Zajdela hepatoma cells. 1 35

The effect(s) of lack of dietary pyridoxine (PX) on the growth of Morris hepatoma no. 7288Ctc was studied. Buffalo strain female rats were fed a diet lacking PX. Pair-fed controls were fed the same diet with PX added. Animals were inoculated with no. 7288Ctc hepatoma cells at 21 days and were sacrificed 16 days later. Host livers and tumors were removed, weights recorded and the activity of tyrosine aminotransferase (TAT; L-tyrosine: 2-oxoglutarate aminotransferase, EC 2.6.1.5) was determined in both host liver and hepatoma. The average weight of 30 hepatomas grown in pair-fed control rats was 11.61 +/- 1.5 g while the average weight of the same number of hepatomas grown in animals fed the PX free diet was 4.73 +/- 0.7 g (P less than 0.001). Further TAT specific activity levels were 39% and 32% higher in host livers and tumors from deficient animals, respectively. The results show that availability of dietary pyridoxine stimulates the growth of this hepatoma and, in addition, exercises a type of control over the expression of TAT activity.
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PMID:Effect of pyridoxine on the growth of Morris hepatoma No. 7288Ctc and enzyme activity. 1 84

Sepharose 4B column with antibody to tyrosine aminotransferase (E.C. 2.6.1.5) (TAT) covalently bound can selectively remove a specific fraction of TAT polysomes from rat liver homogenates. From the polysomes which was adsorbed by immunosorbent one may obtain mRNA containing a segment of poly-adenilate-rich residues, having sedimentation constant of 11--16S. This mRNA may program synthesis of the specific protein in a cell free system. Near 70% of the protein was synthesized in such a system, may react with the antibody to TAT.
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PMID:Extraction of tyrosine aminotransferase mRNA by polyribosome immunosorption on sepharose 4B. 2 21

The influence of denaturation conditions upon the character of partial denaturation of DNA with random base distribution were thoroughly studied. Maps of partial DNA denaturation were obtained at T less than TAT for phage phiB DNA at pH 10.7 and 5.5; Tg9 DNA at pH 8.8; at T less than TAT for phiB DNA at pH 10.9 and Tg9 DNA at pH 8.8. The map quality was better when obtained at higher pH values; the peaks became sharper and higher against the background. We failed to obtain maps of partial denaturation at pH 5.5, T less than TAT. The improvement of the map quality and existence of the partial denaturation maps at T less than TAT at pH 10.9 were explained by the increase of primary melting probability of AT-rich DNA regions. At high pH the denaturation map quality was temperature independent. This was explained by a very weak temperature dependence of primary melting probability for all maps of equal quality. The map quality became worse, when the quantity of loops was increased.
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PMID:[Nature of the easily melted portions of DNA with a quasi-random base sequence]. 2 79

HTC cell variants chosen for their lack of tyrosine aminotransferase (EC 2.6.1.5) (TAT) induction by glucocorticoids were tested for interrelated effects on other glucocorticoid responses: TAT induction by dibutyryl cyclic AMP (dBcAMP) +/- dexamethasone, glutamine synthetase (GS) induction, cyclic nucleotide phosphodieterase (PDE) suppression, inhibition of alpha-aminoisobutyric acid (AIB) uptake, inhibition of plasminogen activator (PA), and induction of mouse mammary tumor virus (MTV). Loss of TAT induction by steroid was accompanied by loss of TAT induction by dBcAMP and of PDE suppression by steroid. In addition, subclones of MTV-infected cells were examined for the effect of the virus on glutamine synthetase (GS) and TAT induction. The virus had no effect on their induction in wild-type cells and no effect on GS induction in the variants. One MTV-infected subclone from a TAT variant, however, showed significant return of TAT induction.
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PMID:Unlinked control of multiple glucocorticoid-induced processes in HTC cells. 3 58

Relying heavily on studies of TAT regulation in cultured rat hepatoma cell lines, we have attempted in this brief review to discuss possible mechanisms for posttranscriptional regulation of glucocorticoid-sensitive enzymes and to chronicle the evidence for and against posttranscriptional mechanisms for specific enzyme induction by glucocorticoids. Initially, mechanisms were considered that would reconcile results showing sensitivity of both induction and deinduction of TAT to inhibitors of RNA synthesis with studies demonstrating first that glucocorticoids regulate the rates of specific enzyme synthesis and, then, that glucocorticoids regulate levels of enzyme-specific mRNA. Such reconciliation proved unnecessary when it was demonstrated that inhibitors of RNA synthesis such as actinomycin D were not specific for RNA synthesis, but also had effects on mRNA turnover and protein metabolism. The bulk of evidence to date establishes that glucocorticoids promote the production of enzyme-specific mRNA for the proteins whose synthesis is regulated by thses steroids. Nevertheless, there is still very little direct evidence that steroids can modulate rates of specific gene transcription. The glucocorticoid stimulation of mouse mammary tumor virus RNA production in cultured cell lines is the only example to date where such a mechanism is supported by RNA-DNA hybridization studies. Posttranscriptional actions of steroids on the turnover, processing, or extranuclear transport of specific mRNA precursors remain potential steps at which glucocorticoids might function. The rapid turnover of some glucocorticoid-regulated enzymes and their mRNAs not only ensures a rapid response to steroid addition or withdrawal, but also subjects these proteins to relatively large fluctuations upon alterations in overall protein or mRNA metabolism. Thus many of the inductions and repressions of hepatic TAT and TO by mediators other than the glucocorticoids may be attributable entirely to nonspecific mechanisms.
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PMID:Posttranscriptional regulation of glucocorticoid-regulated functions. 4 Jan 16

Selected coagulation parameters were measured in 10 women, aged 15-22, who underwent abortion induced by 15-methyl-PGF2 alpha in the 12th-14th week of pregnancy. 250 mcg of the preparation was administered i.m. every 2 hours. Parameters were measured at 6 time intervals: 5 minutes before; 30 minutes, 4 and 8 hours after the initial injection; 2 hours after the completed abortion; and 24 hours after beginning treatment. An increase in bleeding and recalcification time was observed. A significant decrease in platelet count and the number of heparinocytes was recorded until 2 hours after the completed abortion; these parameters then showed an increase 24 hours after the beginning of treatment. A significant increase in the heat fibrin level was recorded up to 4 hours after injection, followed by a significant decrease from 8 hours after injection to 2 hours after the completed abortion (p.05). After a continued decrease in prothrombin levels up to 2 hours after the completed abortion, a statistically significant increase was observed (p.01). No significant changes in the TAT or PTT were observed.
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PMID:[Determination of selected coagulation parameters in induced abortion by means of 15-methyl-PGF2 alpha]. 8 92

A survey of clinical psychologists determined that both objective and projective tests were used with high frequency. The two tests clinicians most frequently recommended clinical students learn to administer were projective (the Rorschach and the TAT) and, among the 10 most frequently recommended tests, projective tests were recommended approximately 30% more often than objective tests. Clinicians who were frequent test users recommended both objective and projective tests more often than those not using tests. Clinicians doing substantial teaching and research tended to recommend projective tests less often than clinicians not engaged in those activities. Behavior therapists recommended projective tests less often than eclectic, Freudian, and neo-Freudian therapists.
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PMID:The status of psychological testing in clinical psychology: relationships between test use and professional activities and orientations. 34 83


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