Patent ID: 7468260

Claim:
A method of analyzing and/or isolating a DNA sequence having a stable expression-enhancing quality, the method comprising the steps of: a) cloning DNA fragments into vectors at a location between i) a DNA sequence comprising a binding site for a repressor protein, which binding site comprises a LexA-binding site or a GAL4-binding site, and wherein the repressor protein is involved in the induction of gene-transcription repressing chromatin, and wherein the repressor protein comprises a fusion protein comprising a part binding a LexA-binding site or a part binding a GAL4-binding site, and ii) a reporter gene comprising a promoter, resulting in a variety of fragment-comprising vectors; b) introducing the vectors into host cells; c) subjecting the host cells to a selection step in order to identify host cells comprising vectors comprising a DNA sequence having a stable expression-enhancing quality, wherein the repressor protein is present in the host cells; and d) isolating from the vectors the DNA sequence having a stable expression-enhancing quality.