Tg(tetO-DBT)525AGeh

The tetO-DBT transgene contains a tetracycline response element and minimal human CMV promoter controlling a human E2 subunit (DBT gene) cDNA which has been modified to contain a 4x alanine linker followed by a c-myc epitope tag at the carboxy terminus to facilitate detection and an SV40 late polyadenylation sequence to increase mRNA stability. Levels of the human E2 protein are approximately equal to mouse E2 protein in livers of control mice. However, when crossed to animals that express a transgene encoding the tetracycline-regulated transactivator protein (Tg(tTALap)5Bjd) and are homozygous for a knockout allele of mouse E2 (Dbttm1Geh) are treated with doxycycline, the E2 protein levels correlate with only ~5-6% of normal branched-chain keto acid dehydrogenase (BCKDH) activity. It is one hypothesis that the addition of the c-myc tag interferes with BCKDH subunit assembly (ie. interaction of the human E2 subunit with mouse E1 and E3 complexes), thus reducing enzymatic activity. (J:119973)