[31] Secreted placental alkaline phosphatase as a eukaryotic reporter gene

This chapter describes the use of a novel indicator gene, producing a secreted form of the human enzyme placental alkaline phosphate, that believes offers a number of advantages. These include very high stability, efficient secretion by all cells tested, and the availability of a simple, inexpensive, and highly quantitative assay that does not require any unusual equipment or reagents. A major focus of the current molecular biological research is the identification and functional dissection of the cis-acting sequences and trans-acting factors that regulate eukaryotic gene expression in vivo. A common method of addressing this question is to link the regulatory sequence of interest, e.g., an inducible promoter/enhancer element, to a reporter gene. Several alternate or complementary reporter gene systems have been proposed. Among the more prevalent are the genes for the intracellular enzymes β-galactosidase, luciferase and the secreted protein human growth hormone. This chapter describes SEAP, a novel indicator gene producing secreted alkaline phosphatase. The SEAP gene has several advantages when compared to CAT or to other prevalent reporter genes.