A major success story of modem molecular biology is the development of technologies to clone and express specific genes. Current applications of recombinant gene products cover a wide spectrum, including gene therapy, production of bioactive pharmaceuticals, synthesis of novel biopolymers, agriculture and animal husbandry, and so on. Inherent in bringing these appli cations to fruition is the need to design expression constructs that will per mit the ready and specific detection and isolation of the defined recombinant gene products. Recombinant Protein Protocols grows out of the need for a laboratory manual on the detection and isolation of recombinantly expressed genes that covers both the background information and the practical laboratory recipes for these analyses. In this book, detailed and contemporary protocols are col lected to provide the reader with a wide-ranging number of methodologies to enhance the detection and isolation of their gene product(s) of interest. A large number of molecular tags and labels and their usage are described, including enzymes, ligand-binding moieties, immunodetectable molecules, as well as methods to detect interactive proteins, and gene expression-mediated alter ations in cellular activity. Chapters on in situ detection of gene expression deal with technologies that are currently being applied to the study of gene function and activity. Highlights of applications for recombinant gene expres sion technologies are provided to give readers exciting perspectives on the future of such technologies.