Fig. 3.

Expression of human CTP synthetase 1 and human CTP synthetase 2 proteins in S. cerevisiae. The ura7Δ ura8Δ mutant bearing plasmids with the yeast URA7 gene (strain GHY52) or the human CTPS1 (strain GHY55) or CTPS2 (strain GHY56) genes were grown to the exponential phase of growth. Cell extracts were prepared and samples (20 μg of protein) were subjected to SDS-PAGE, followed by transfer to PVDF membrane. The membrane was probed with anti-His₆ antibodies to detect the His₆-tagged human CTP synthetase 1 (hCTPS1) and human CTP synthetase 2 (hCTPS2) proteins (left). The membrane was stripped of the anti-His₆ antibodies and reprobed with anti-Ura7p antibodies to detect the yeast URA7-encoded CTP synthetase (yCTPS) protein (middle). Prior to probing with the antibodies, the PVDF membrane was stained with Ponceau S to detect the total amount of protein on the membrane (right). The data shown were representative of two independent experiments.