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

Purified gamma-aminobutyric acid aminotransferase (GABA-AT) from pig brain under certain conditions gave a single band on 12% NaDodSO(4)-PAGE, whereas two or three distinct bands were observed on 7.5% native PAGE. These multiple active species were isolated by 5% preparative gel electrophoresis and characterized by N-terminal sequencing and MALDI-TOF mass spectrometry. The results indicate that these active enzyme species are not GABA-AT isozymes in pig brain, but are the products of proteolysis of the N-terminus of GABA-AT, differing by 3, 7, and 12 residues from the full sequence (as deduced from the cDNA), respectively. Conditions for obtaining the nontruncated GABA-AT were found, and the potential cause for the proteolysis was determined. It was found that Na(2)EDTA inhibits the N-terminal cleavage during GABA-AT preparation from pig brain. The presence of Triton X-100 in the homogenization step is partially responsible for this proteolysis, and Mn(2+) strongly enhances the protease activity, suggesting the presence of a membrane-bound matrix metalloprotease that causes the N-terminal cleavage.
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PMID:The multiple active enzyme species of gamma-aminobutyric acid aminotransferase are not isozymes. 1066 4

1. The aim of this study was to find taurinergic compounds that do not interact with brain GABA ergic systems. 2. Washed synaptic membranes (SM) from whole rabbit brain were able to bind [(3)H]muscimol. Saturation experiments of the binding of [(3)H]GABA to GABA(B) receptors showed that SM possess two binding components; twice Triton X-100-treated SM contained 0.048 mmol endogenous taurine/kg protein and bound [(3)H]taurine in a saturable manner (K(d)=249.0+/-6.3 nM and B(max)=3.4+/-1.0 pmol mg(-1) prot). 3. Among the 19 structural analogues of taurine, 6-aminomethyl-3-methyl-4H-1,2,4-benzothiadiazine 1,1-dioxide (TAG), 2-aminoethylarsonic (AEA), 2-hydroxyethanesulfonic (ISE) and (+/-)cis-2-aminocyclohexane sulfonic acids (CAHS) displaced [(3)H]taurine binding (K(i)=0.13, 0.13, 13.5 and 4.0 micro M, respectively). These analogues did not interact with GABA(A) and GABA(B) receptors and did not affect taurine- and GABA-uptake systems and GABA-transaminase activity. 4. 3-Aminopropanesulfonic acid (OMO), beta-alanine, pyridine-3-sulfonic acid, N,N,N-trimethyltaurine (TMT), 2-(guanidino)ethanesulfonic acid (GES), ethanolamine-O-sulphate, N,N-dimethyltaurine (DMT), taurine and (+/-)piperidine-3-sulfonic acid (PSA) inhibited [(3)H]muscimol binding to GABA(A) receptors with different affinities (K(i)=0.013, 7.9, 24.6, 47.5, 52.0, 91.0, 47.5, 118.1 and 166.3 micro M, respectively). Taurine, 2-aminoethylphosphonic acid, DMT, TMT and OMO inhibited the binding of [(3)H]GABA to GABA(B) receptors with K(i)'s in the micro M range (0.8, 3.5, 4.4, 11.3 and 5.0, respectively). GES inhibited taurine uptake (IC(50)=3.72 micro M) and PSA GABA transaminase activity (IC(50)=103.0 micro M). 5. In conclusion, AEA, TAG, ISE and CAHS fulfill the criteria for taurinergic agents.
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PMID:Interactions of taurine and structurally related analogues with the GABAergic system and taurine binding sites of rabbit brain. 1268 73