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γ-Aminobutyrate (GABA), a four carbon amino acid, was discovered in brain tissue in 1950. GABA is an inhibitory neurotransmitter in the mammalian CNS. GABA is produced mainly through enzymatic decarboxylation of glutamic acid by glutamic acid decarboxylase (GAD), and synthesized by the degradation of putrescine (1,4-diaminobutane), one of the polyamines. It provides γ-aminobutyraldehyde (γ-ABAL), substrate for the synthesis of GABA by y-amino-buevaBdehyde dehydrogensse (U-ABALDH). We purified γ-ABALDH, another synthetic enzyme for GABA, from the bovine brain and prepared an antibody for γ-ABALDH from rabbits. We also attempted the NH₂-terminal sequencing of γ-ABALDH and were successful in producing the oligonucleotide probes based on the N-terminal sequence determined. 36 mer-oligo-nucleotides complementary to the mRNA were synthesized, and radiolabelled at the 5´end with ^(32)P. Then an in situ hybridization technique was applied to deteet γ-aminobutyraldehyde dehydrogenase mRNA in the bovine brain tissue. Cells containing mRNA of γ-ABALDH were found in many regions of bovine brain tissue, the results being similar to those from immunostaining.
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