Vectors for expression and secretion of FLAG epitope-tagged proteins in mammalian cells

The FLAG peptide, AspTyrLysAspAspAspAspLys, has been used as an epitope tag in a variety of cell types. The modification of the cytomegalovirus (CMV) promoter containing vector, pCMV5, to create two transient expression vectors designed for secretion and intracellular expression of FLAG-fusion proteins in mammalian cells is described. As a functional test, the bacterial alkaline phosphatase gene was cloned into both vectors, and anti-FLAG monoclonal antibodies were used for detection of FLAG epitope-tagged bacterial alkaline phosphatase in mammalian cells. In addition, secreted bacterial alkaline phosphatase was purified from the extracellular medium by anti-FLAG affinity chromatography.