MOLECULAR-CLONING OF RAT KYNURENINE AMINOTRANSFERASE - IDENTITY WITH GLUTAMINE TRANSAMINASE-K

The enzyme kynurenine aminotransferase (KAT) catalyses the conversion of L-kynurenine to kynurenic acid. A combination of polymerase chain r eaction techniques and hybridization screening was used to isolate a c DNA clone encompassing the entire coding region of KAT from rat kidney . Identification of the cDNA as coding for KAT was based both on the c omparison of amino acid sequences obtained from purified rat KAT and o n the expression of KAT activity in COS-1 cells transfected with the c DNA. RNA blot analysis indicated that KAT mRNA is widely expressed in rat tissues. Cultured cells transfected with the cDNA for KAT also sho wed glutamine transaminase K activity. Based mainly on sequence data, these results demonstrate that rat kidney KAT is identical with glutam ine transaminase K.