Detection of Proteins in cDNA Libraries
Screening a cDNA library using an antibody can work very well. The bacteria in cDNA libraries have been given a gene insert that is the same sequence of nucleotides as the mRNA that is translated to make proteins in the original organism. The cDNA is inserted behind a promoter sequence in the lac Z gene of the plasmid. Therefore, the bacteria can transcribe the inserted gene, and translate the mRNA the inserted gene encodes to make the same protein found in the original organism. The bacteria do not encounter introns that they lack the capabilities to splice out because our cDNA was copied from mRNA after the introns were removed. Therefore, if we have an antibody that will bind to the protein encoded by the gene of interest, making a cDNA library and then screening it with the antibody is a valid gene cloning strategy.