AFFINITY PURIFICATION AND CHARACTERIZATION OF CIF, AN INSECT IMMUNORESPONSIVE FACTOR WITH NF-KAPPA-B-LIKE PROPERTIES

1. A rapid DNA affinity purification procedure was worked out for the purification of the Cecropia Immunoresponsive Factor (CIF) from the pupae of Hyalophora cecropia. 2. CIF consists of a single polypeptide chain of 65 kDa and is present as a homodimer under native conditions. 3. CIF binds to the kappa-B-like sequences upstream of the H. cecropia immune genes with the following order of affinity: attacin kappa-B > lysozyme kappa-B > cecropin A kappa-B > cecropin B kappa-B. 4. The purified CIF also strongly binds to the kappa-B sequences from both the immunoglobulin kappa light chain gene and the MHC class I gene. 5. The DNA binding of CIF can be inhibited by antisera directed against NF-kappa-B-related proteins. 6. The cytoplasmic factor Cl, co-purified from the affinity column, contains two polypeptide chains, one of which has the same molecular weight as CIF.