An Expression Vector Encoding a lacZ Reporter Gene Facilitates Identification of Stable, High-Producing CHO Cell Clones

Abstract We describe a vector and a streamlined procedure for isolating high-producing stable mammalian cell transfectants. The vector encodes the Escherichia coli lacZ gene as a reporter. We show that levels of β-galactosidase activity, assayed in situ in clonal isolates, can be used to identify clones producing high levels of the protein of interest (in this case, soluble human CD4 protein).