Cloning of Homologous Genes by Gene-Capture PCR

Conventional procedures to isolate a gene belonging to an ortholog family usually imply the use or the construction of double-stranded cDNA libraries derived from a specific mRNA source of interest (cells or tissues) (1 ). The double-stranded DNA library plated on various membranes is screened by filter hybridization with a radiolabeled probe (1 ) derived from the known homologous gene. Clones or plaques hybridizing with the probe are then isolated and sequenced to find the gene of interest. This approach is time-consuming and a large number of false positive clones might be obtained, given that no homology is a priori available, especially when the homologous probe contains a short and stable stretch of a sequence sharing clustered homology with both strands of the cDNA library. Alternatively, homologous genes may be isolated by PCR, but only when specific primers are available.