Tissue-specific binding of a nuclear factor to the insulin gene promoter

Using a DNA-binding gel mobility shift assay, a protein-DNA complex was detected using the rat II insulin promoter and a nuclear extract from rat insulinoma cells. This complex was detected using extracts from other insulin-producing cell lines but was not found using nuclear extracts from non-insulin-producing pancreatic cell lines or other cell types. Binding of the tissue-specific protein to the labelled promoter fragment was effectively competed by both rat and human insulin genes but not by the SV40 TATA box. This protein-DNA interaction may be involved in tissue-specific regulation of insulin gene expression.