THE PROTOONCOGENE PRODUCT, PEBP2-BETA CBF-BETA, IS MAINLY LOCATED IN THE CYTOPLASM AND HAS AN AFFINITY WITH CYTOSKELETAL STRUCTURES/

The Pebp62/Cbfb gene encodes the non-DNA binding beta subunit of the h eterodimeric transcription factor, PEBP2/CBF, and has been implicated in a subtype of human acute myeloid leukemia, as well as being indispe nsable for the development of definitive hematopoiesis in the murine f etal liver, By examining a subcellular localization of the PEBP2 beta/ CBF beta protein in tissue culture cells, we could reveal an additiona l aspect of the protein other than to be a subunit of a transcription factor, Immunoblot and immunocytochemical staining showed that PEBP2 b eta/CBF beta was mostly present in the cytoplasm, This PEBP2 beta/CBF beta was free from its DNA-binding partner, the cc subunit of PEBP2/CB F, as judged by the electrophoretic mobility shift assays, Furthermore , a significant amount of PEBP2 beta 1/CBF beta was retained in the cy toskeleton preparation after detergent extraction of the cells and was found by double immunofluorescence to colocalize with the F-actin on stress fibers and the vinculin in membrane processes, Thus, the presen t study extends PEBP2 beta/CBF beta to be a cytoskeleton-affinitive as well as nuclear protein, The implications of these results are discus sed.