Molecular cloning of polymerase chain reaction fragments with cohesive ends

The transfection of expressible DNA into cell lines has allowed studies of gene expression and interaction that are often very difficult or impossible using the endogenous genes. The importance of this method is highlighted by the observation that, in a recent issue of Cell, 10 out of 14 articles reported data obtained through DNA transfer techniques (1). The production of DNA constructs for transfection requires the availability of cloned DNA sequences including promoters, enhancers, transcribed sequences, and 3' elements. Many investigations also use constructs in which promoters are recombined with heterologous reporter genes, such as luciferase or chloramphenicol acetyl transferase.