Isolation of a human brain cDNA for glutamate dehydrogenase

A cDNA has been isolated from a human brain expression library using anti-bovine glutamate dehydrogenase (GDH) antibodies. The cDNA has an open reading frame of 774 nucleotides, which codes for 258 amino acids. The 258-amino-acid sequence is 95% homologous to the carboxy terminus of human liver GDH. This high degree of homology indicates that the cDNA codes for brain GDH. Fourteen differences between the amino acid sequence deduced from this cDNA and the sequence reported for human liver GDH suggest that there may be two active human GDH genes. A cRNA probe synthesized from the cDNA detects a 3.7-kilobase (kb) mRNA from human brain. Rat liver and kidney each contain two GDH mRNAs, 3.5 and 2.8 kb, respectively. The 3.5-kb transcript is prominent in rat brain, whereas the 2.8-kb transcript is barely detectable, a result suggesting that GDH gene expression is differentially controlled in rat brain.