[Nuclear proteins preferentially bound to the beta-globin gene: cellular specificity and variation during terminal differentiation of mouse erythroblasts].

Restriction fragments of the mouse beta major globin gene and of the long terminal repeat (LTR) DNA fragment of the mouse mammary tumor provirus as a control, were used to analyze the specificity of DNA-protein interactions in nuclear extracts of mouse erythroleukemia (MEL) cells and of other differentiated mouse cultured cell lines. After gel electrophoresis and transfer to nitrocellulose, DNA-binding proteins with a preferential affinity for the cloned beta-globin genomic sequence were characterized and related to the level of globin gene expression during induction of differentiating mouse erythroblasts. Two proteins (110 K and 75 K) appear in differentiated MEL cells while another one (100 K), for which we have localized the binding site on the beta-globin gene, is present only in immature MEL cells.