Biosynthesis of 4-aminobutyrate aminotransferase.
Mitochondrial 4-aminobutyrate aminotransferase was synthesized in a cell-free reticulocyte lysate using polysomal RNA isolated from pig brain. Its primary translation product has a higher molecular mass than the mature enzyme. The difference in relative molecular mass is approximately 2000 as revealed by SDS/polyacrylamide gel electrophoresis. The precursor of 4-aminobutyrate aminotransferase recognizes polyvalent antibodies raised against the mature enzyme. The precursor of 4-aminobutyrate aminotransferase binds pyridoxal-5-P and displays catalytic activity. Enzymatic activity was detected using a sensitive fluorimetric method, which is based on the formation of condensation products between succinic semialdehyde and cyclohexane-1,3-dione. It is concluded that removal of an extra peptide from the precursor is not an obligatory first step in the production of biological active species.
D000612:4-Aminobutyrate Transaminase / Q000096:biosynthesis* / Q000302:isolation & purification; D000818:Animals; D001921:Brain / Q000201:enzymology; D002384:Catalysis; D002474:Cell-Free System; D004591:Electrophoresis, Polyacrylamide Gel; D004792:Enzyme Precursors / Q000378:metabolism; D007120:Immunochemistry; D008928:Mitochondria / Q000201:enzymology; D014176:Protein Biosynthesis; D013552:Swine
D004792:Enzyme Precursors; D000612:4-Aminobutyrate Transaminase