Specific protein-DNA interaction at four sites flanking the chicken lysozyme gene

Cloned DNA containing 22.2 kb of the chicken lysozyme gene region was screened with use of a nitrocellulose filter binding technique for specific recognition by nuclear DNA binding proteins from chicken oviduct cells. The analysis showed specific retention of four restriction fragments (BS1-BS4), which map approximately 6.1 and 3.9 kb upstream from the transcription start, and 2.8 and 6.2 kb downstream from the poly(A)-addition point of the lysozyme gene. The four DNA fragments mutually served as efficient competitors, indicating that only one class of proteins is involved in the recognition of all four sites. An apparent binding constant of KD = 6 X 10(-12) M was estimated for one of the binding fragments (BS1). Fine mapping of this fragment resolved two closely spaced contact areas at least 43 bp apart.