PROTEINS INTERACTING WITH THE IMMUNOGLOBULIN KAPPA-GENE PROMOTER

Nuclear extracts from murine myeloma cell line NS/0 were found to cont ain three factors capable of specific binding to the oct sequence. The first one, mOct-1, is in its characteristics similar with the human u biquitous factor Oct-1. The other two can be related to the Oct-2 fami ly. The complexes of these factors with DNA probe display different ge l electrophoretic mobility. Factor mOct-2A, similar with the human lym phoid-specific Oct-2A, can specifically bind an Oct-protein-associated factor (OAF) present in the nuclear extract; this protein factor also has nonspecific affinity for DNA and dissociates from the complex wit h Oct-2A in the presence of natural DNA. Oct-1 has no affinity for OAF . Since only Oct-2A activates transcription from the Ig kappa-gene pro moter, it can be supposed that OAF binding is necessary for specific a ctivation of transcription.