An improved Escherichia coli expression vector for the construction and identification of full-length cDNA clones

An Escherichia coli expression vector designed for the efficient synthesis and identification of a full-length cDNA clone is constructed. The vector allows the synthesis of double-stranded cDNAs downstream from the tandem lac control regions employing the vector-primer and linker procedure of Okayama and Berg [Mol. Cell Biol. 2 (1982) 161-170]. Full-length cDNA clones carrying the 5'-noncoding region in addition to the entire coding and 3'-noncoding regions can be expressed in E. coli cells without fusing their coding region to that of E. coli proteins; these clones are identified by colony immunoassay. The entire cDNA insert can be easily excised from the plasmid, since the multiple cloning sites in the vector are duplicated at both ends of the cDNA insert during its synthesis.