Within the last few years, it has become well established that a given nucleic acid binding protein has the potential to interact specifically with more than one target nucleic acid sequence. Various immunoprecipitation techniques have been developed to isolate specific DNA-protein complexes from intact cells (1 –4 ). These studies have allowed for the precise identification of in vivo target genes for a given DNA binding protein. Moreover, they have provided important insights as to the critical nucleotide elements required for DNA binding.
