A nuclear factor which interacts with an AT-cluster in the first intron of rat alpha 2-macroglobulin gene

We have identified a nuclear protein which binds specifically to the first intron of rat alpha 2-macroglobulin gene. The protein became insoluble at low salt concentration retaining the binding specificity. Its molecular weight was estimated to be 22 kilodalton by a protein blotting procedure. The binding site of the protein determined by DNase I footprinting was an AT-strech which shared 80% homology with the cleavage consensus of Drosophila topoisomerase II.