Expression of the murine prostaglandin (PGH) synthase-1 and PGH synthase-2 isozymes in cos-1 cells.

Plasmid vectors were constructed which allowed expression of the mouse prostaglandin endoperoxide (PGH) synthase-1 and PGH synthase-2 isozymes in cos-1 cells. Efficient expression of the PGHS-2 isozyme required the truncation of the entire 3'-untranslated region of the PGHS-2 cDNA, possibly due to the presence of multiple AUUUA sequences which may destabilize the PGHS-2 mRNA. The length of the 3'-untranslated regions of the murine and ovine PGHS-1 isozymes, which do not contain AUUUA sequences, did not affect the efficiency of expression of these proteins. The murine PGHS-2 isozyme catalyzes the same cyclooxygenase and hydroperoxidase activities as the ovine and murine PGHS-1 isozymes. The maximal activities of the mouse enzymes expressed in cos-1 cells was about equal, but both were only about a third that seen with the sheep enzyme. Whether this reflects differences in the turnover rate of the mouse and sheep enzymes, or differences in the efficiency of expression in cos-1 cells is not known.