Genome Walking by PCR
Genome walking by PCR makes it possible to clone genomic sequences flanking a known DNA sequence. It is useful for example in the case of a gene tagged by a transposon (or, for plants, an insertion of T-DNA) (see Profile 45), or even for cloning the promoter of a gene for which the cDNA is not known. This technique can be used to characterize the sequence located upstream (5'-P) as well as the sequence located downstream (3-OH) of the known sequence. It is a quick approach, highly sensitive, specific, and requiring little genomic DNA. It has the advantage of being operational for DNA of an individual (e.g., a mutant) for which a genomic library is not always available.