NF-κB protein purification from bovine spleen: Nucleotide stimulation and binding site specificity

The activity of the enhancer for the κ immunoglobulin light chain gene critically depends on the presence in the nucleus of the NF-κB protein. We purified NF-κB over 50,000-fold and identified two protein species, 42 and 44 kDa, that could be eluted and renatured from a sodium dodecyl sulfate/polyacrylamide gel to give specific DNA-binding activity. Binding of the purified bovine NF-κB as well as that from human and murine B- or T-lymphoid cell extracts was dramatically stimulated by nucleoside triphosphates. This effect distinguished NF-κB from a related factor, H2-TF1. Purified NF-κB interacted efficiently with regulatory sequences that function during either B- or T-lymphocyte activation, including the human immunodeficiency virus enhancer and a NF-κB binding site we detected in the interleukin 2 enhancer.