Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.6.1.19 (GABA transaminase)
 808 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The amino acid sequence predicted from a rat liver cDNA library indicated that the precursor of beta-AlaAT I (4-aminobutyrate aminotransferase, beta-alanine-oxoglutarate aminotransferase) consists of a mature enzyme of 466 amino acid residues and a 34-amino acid terminal segment, with amino acids attributed to the leader peptide. However, the mass of beta-AlaAT I from rat brain was larger than that from rat liver and kidney, as assessed by Western-blot analysis, mass spectroscopy and N-terminal sequencing. The mature form of beta-AlaAT I from the brain had an ISQAAAK- peptide on the N-terminus of the liver mature beta-AlaAT I. Brain beta-AlaAT I was cleaved to liver beta-AlaAT I when incubated with fresh mitochondrial extract from rat liver. These results imply that mature rat liver beta-AlaAT I is proteolytically cleaved in two steps. The first cleavage of the motif XRX( downward arrow)XS is performed by a mitochondrial processing peptidase, yielding an intermediate-sized protein which is the mature brain beta-AlaAT I. The second cleavage, which generates the mature liver beta-AlaAT I, is also carried out by a mitochondrial endopeptidase. The second peptidase is active in liver but lacking in brain.
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PMID:The mature size of rat 4-aminobutyrate aminotransferase is different in liver and brain. 1044 91

In tomato, free amino acids increase dramatically during fruit ripening and their abundance changed differentially. More evident is L-glutamate which gives the characteristic "umami" flavor. Glutamate is the principal free amino acid of ripe fruits of cultivated varieties. In this paper, we examined the capacity of tomato fruits to process endogenous as well as exogenous polypeptides during the ripening transition, in order to analyze their contribution to the free amino acid pool. In addition, the activity of some enzymes involved in glutamate metabolism such as gamma-glutamyl transpeptidase (gamma-GTase), glutamate dehydrogenase (GDH), alpha-ketoglutarate-dependent gamma-aminobutyrate transaminase (GABA-T), alanine and aspartate aminotransferases was evaluated. Results showed that peptidases were very active in ripening fruits, and they were able to release free amino acids from endogenous proteins and glutamate from exogenously added glutamate-containing peptides. In addition, red fruit contained enough gamma-GTase activity to sustain glutamate liberation from endogenous substrates such as glutathione. From all the glutamate metabolizing enzymes, GDH and GABA-T showed the higher increase in activities when the ripening process starts. In summary, tomato fruits increase free amino acid content during ripening, most probably due to the raise of different peptidase activities. However, glutamate level of ripe fruit seems to be mostly related to GDH and GABA-T activities that could contribute to increase L-glutamate level during the ripening transition.
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PMID:Free amino acid production during tomato fruit ripening: a focus on L-glutamate. 1987 14