which is herein incorporated by reference or dna probes bodner et al cell 55 505 518 1988 the entirety of which is herein incorporated by reference in addition an in situ screening procedure has been used and has facilitated the isolation of sequence specific dna binding proteins from various plant species gilmartin et al plant cell 4 839 849 1992 the entirety of which is herein incorporated by reference schindler et al embo j 11 1261 1273 1992 the entirety of which is herein incorporated by reference an in situ screening protocol does not require the purification of the protein of interest vinson et al genes dev 2 801 806 1988 the entirety of which is herein incorporated by reference singh et al cell 52 415 423 1988 the entirety of which is herein incorporated by reference steps may be employed to characterize dna protein interactions the first is to identify promoter fragments that interact with dna binding proteins to titrate binding activity to determine the specificity of binding and to determine whether a given dna binding activity can interact with related dna sequences sambrook et al molecular cloning a laboratory manual 2 nd edition cold spring harbor laboratory press cold spring harbor n y.