A far upstream ovalbumin enhancer binds nuclear factor-1-like factor.

Band-shifting and DNase I footprinting analyses detected a specific DNA binding protein extracted from oviduct nuclei that binds to the ovalbumin gene 5' sequence between -1094 and -1125. This "-1100" fragment, when inserted upstream of the SV40 or ovalbumin promoters fused to a chloramphenicol acetyltransferase reporter gene, enhances chloramphenicol acetyltransferase activity 5-10-fold following transfection into CV1 cells. The sequence to which the oviduct factor binds contains a nuclear factor-1 (NF-1) half-site (GCCAA). An oligonucleotide matching the sequence of the adenovirus NF-1 binding site competed for binding to the -1100 footprinted region with a higher affinity than an oligonucleotide for the -1100 region itself. Similarly, the -1100 region oligonucleotide also competes for binding of the factor to the NF-1 oligonucleotide. These data suggest that the oviduct factor which binds to the -1100 region is an NF-1-like protein that serves as a steroid hormone-independent enhancer of the ovalbumin gene transcription.