Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P17174 (aspartate aminotransferase)
 14,872 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The nucleotide sequence of ornithine aminotransferase mRNA from rat liver, including the entire coding and 3' untranslated regions, was determined from two overlapping cDNA clones. The mRNA encodes a precursor polypeptide of 439 amino acid residues with a molecular weight of 48,332. The deduced amino acid composition of the proposed mature enzyme sequence (residues 35 through 439) was in good agreement with that reported for the purified protein. The amino-terminal segment of the precursor corresponding to residues 1 through 34 has an overall positive charge, containing 6 basic residues and only a single acidic residue, and is postulated to be the mitochondrial leader sequence. The first 22 amino acid residues of the proposed leader sequences share 54% homology with the leader peptide of rat ornithine transcarbamylase precursor and more limited homology to the leader peptides of other nuclear-encoded mitochondrial matrix proteins. Homology was also observed between residues 286 through 362 ornithine aminotransferase precursor and a region containing the pyridoxyl phosphate binding domain of mitochondrial aspartate aminotransferase.
 ...
PMID:Sequence of the precursor to rat ornithine aminotransferase deduced from a cDNA clone. 384 Apr 76

The effects of cortical lesions and intrastriatal kainic acid injections on various striatal enzyme activities were investigated. Ornithine aminotransferase decreased concomitantly with glutamate uptake in decorticated and chronic kainic acid-treated rats. It was also decreased in acute kainic acid-lesioned striatum where glutamate uptake was unaffected. Aspartate aminotransferase, however, decreased only after acute kainic acid treatment. Results for glutamate uptake, glutamate decarboxylase, and choline acetyltransferase were in agreement with previous findings. These results suggest that ornithine may act as a precursor for glutamate in nerve terminals, although the nonspecific localization does not allow ornithine aminotransferase to be a convenient biochemical marker. The decrease in aspartate aminotransferase is thought to be due to the widespread cell degeneration after acute kainic acid. Aspartate aminotransferase activities were also found to be reduced in the frontal cortex, caudate nucleus and putamen of Huntington's disease brains.
 ...
PMID:Effects of kainic acid injection and cortical lesion on ornithine and aspartate aminotransferases in rat striatum. 613 Nov 42

Rats having a protein-free diet available ad libitum were fed a daily casein meal at the beginning of either the light- or the dark-phase of the day. A control group received a mixed-diet ad libitum. In all three groups, daily food ingestion was the same and casein corresponded to 12% of total intake. Liver activities of alanine, aspartate, ornithine and tyrosine aminotransferase, ornithine decarboxylase and serine dehydratase were assessed. In mixed-fed controls, all activities were low. Tyrosine aminotransferase and ornithine decarboxylase exhibited clear circadian rhythms of low amplitude. Feeding casein as a concentrated meal had no effect on aspartate aminotransferase. It depressed alanine aminotransferase and serine dehydratase activities. Tyrosine aminotransferase and ornithine decarboxylase exhibited rapid and strong stimulatory responses but, within 12 hours, returned to levels similar to those observed in mixed-fed controls. Ornithine aminotransferase was increased in the group receiving the casein meal during the light phase. It is concluded that the capacity for amino acid catabolism remains low in separately-fed animals, and that only tyrosine and especially ornithine, which may become limiting for urea synthesis, are actively metabolized. Thus, when high fluxes of amino acids reach the liver following the absorption of the casein meal, more amino acids are available for incorporation into newly synthesized proteins.
 ...
PMID:Activity of several enzymes of amino acid catabolism in the liver of rats fed protein as a meal. 613 52

Ornithine aminotransferase is shown to bind 1 mol of amino[14C]hexynoate per mol of coenzyme in the 'suicide' inactivation process. At the same time the coenzyme pyridoxal phosphate becomes irreversibly bound to the enzyme protein. Apart from the inactivation, the labelled enzyme is indistinguishable from native ornithine aminotransferase by several separation techniques. Because the rate of degradation of the labelled enzyme is the same as that of the normal enzyme it is concluded that loss of coenzyme does not initiate turnover. Free aminohexynoate is rapidly eliminated from the liver, and 70% of the compound is excreted unchanged in 7.5 h. Inactivated ornithine aminotransferase accounts for 11% of the total labelled liver protein and significant amounts of label are found in aspartate aminotransferase which is also extensively inactivated. The rate of return of enzyme activity is determined and found to be more rapid than expected for a process in which the enzyme is synthesized at a constant rate and degraded in a single, first-order process.
 ...
PMID:An investigation of the properties of ornithine aminotransferase after inactivation by the 'suicide' inhibitor aminohexynoate and use of the compound as a probe of intracellullar protein turnover. 684 11