Identification of a mitochondrial form of kynurenine aminotransferase/glutamine transaminase K from rat brain.
A soluble aminotransferase with kynurenine aminotransferase (KAT) activity has been recently isolated from rat brain. This enzyme corresponds to a cytosolic form of glutamine transaminase K (GTK). In addition to the cytosolic enzyme, a mitochondrial-associated form of this KAT/GTK also exists. In the present work we have isolated a rat brain cDNA clone encoding a KAT/GTK enzyme identical to the soluble form but carrying an additional stretch of 32 amino acids at its NH2-terminus. Several structural features of this sequence resemble those of leader peptides for mitochondrial import. Evidence that the isolated cDNA encoded for mitochondrial KAT/GTK was obtained after transfection of HEK-293 cells with the cDNA coding for this new KAT/GTK isoenzyme. In fact, a significant enrichment of both KAT and GTK enzymatic activities was found in the crude mitochondrial fraction of the transfected cells.
Malherbe
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P
Pharma Division, F. Hoffmann-La Roche Ltd., Basel, Switzerland.
Alberati-Giani
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D
Köhler
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Cesura
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AM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000201:enzymology*; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D015870:Gene Expression; D008190:Lyases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D051381:Rats; D000637:Transaminases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014162:Transfection
D018076:DNA, Complementary; D000637:Transaminases; C427605:glutamine - phenylpyruvate transaminase; C021481:kynurenine-oxoglutarate transaminase; D008190:Lyases