Polymerase Chain Reaction Screening of Genomic Libraries for Adrenergic Receptor Genes

In the search for novel G-protein-coupled receptor genes, two common approaches have worked fairly well and are relatively easy to perform. One method is homology-based screening approaches, which utilize low-stringency screening of genomic or cDNA libraries with a known cDNA probe. The other method uses polymerase chain reaction-(PCR) based approaches on the same genomic or cDNA libraries. The latter approach is more sensitive based on the inherent amplification in the PCR process, and the strategic design of the PCR primers can ultimately lead to more novel sequences being obtained. The method can also be applied directly on mRNA after it is transcribed into first-strand cDNA. However, libraries offer the assurance that once a PCR product is obtained, the gene must be present in the library because it generated the template needed in the PCR process. This approach presents a quicker means of obtaining a full-length clone.