Bacterial Expression of Functional Membrane-Bound Thromboxane Synthase Having Intact Sequence and Truncated N-Terminal Hydrophobic Segment

A full-length cDNA for human placental thromboxane synthase and a shortened cDNA lacking the sequence corresponding to the N-terminal 2-29 amino acids were expressed in Escherichia coli using a pCW expression vector. Both intact and truncated recombinant enzyme were found in the membrane fraction and were catalytically active. These results suggest that the N-terminal hydrophobic segment, a proposed membrane anchor for P-450 enzymes, is not solely responsible for attachment of thromboxane synthase to the membrane and is not required for the proper protein folding or the enzyme activity.