Molecular cloning and functional expression of bovine brain GABA transaminase

We isolated a cDNA that encodes the bovine brain gamma -aminobutyrate trans aminase (GABA-T; EC 2.6.1.19) from the lambda gt 11 eDNA library, which sho wed a high degree of sequence similarity to the corresponding enzymes from various sources. Northern blot analysis revealed two differentially express ed GABA-T transcripts of approximately 2.0 and 6.0 kb in the bovine tissues . Southern blot analysis indicates that the two GABA-T transcripts are enco ded in a greater-than 10-kb, single-copy gene. Bovine GABA-T cDNA was expre ssed in E. coli using the pGEX bacterial-expression vector system. The over expressed GABA-T was enzymatically active after purification, and it had ve ry similar kinetic parameters when compared with those of other mammalian G ABA-Ts.