BOX-I AND BOX-II MOTIF FROM MYELIN BASIC-PROTEIN GENE PROMOTER BINDS TO NUCLEAR PROTEINS FROM RODENT BRAIN

The box I and II motif located within the promoter of the myelin basic protein gene contains a simian virus 40 T-antigen-binding site, a Myo D/E2a-binding site, and a glucocorticoid receptor-binding site. We hav e found proteins within nuclear extracts from adult mouse brain, rat e mbryonic cerebral cortex in culture, and a mouse oligodendrocyte-like cell line that bind to a P-32-labeled synthetic DNA fragment containin g the sequences of the box I and II motif. Three major complexes (A, B , and C) were seen in gel-shift assays. Only complexes A and B were co mpeted out by the unlabeled box I and II fragment or by another synthe tic DNA fragment that also contains sequences similar to a glucocortic oid receptor-binding site. Therefore, complexes A and B were thought t o be specific. The expression pattern of the proteins responsible for the formation of these complexes was also assessed during development in mouse brain.