FUNCTIONAL EXPRESSION OF THE GUINEA-PIG 11-BETA-HYDROXYLASE IN COS-1 CELLS

We expressed a guinea pig 11 beta-hydroxylase cDNA (1) in COS-1 cells. In order to find the optimal expression system we compared three expr ession plasmids, each driven by a different promoter. Although promote rs exhibited different transcriptional activities this did not result in different enzymatic activities. Upon cotransfection with bovine adr enodoxin a 5-fold increase of enzyme activity was achieved. A comparis on with the bovine 11 beta-hydroxylase clearly demonstrated that the g uinea pig enzyme was not able to produce significant amounts of 18-hyd roxylated and 18-oxidized products from deoxycorticosterone under the experimental conditions used.