HISTONE H-1 BINDING AT THE 5' END OF THE RAT ALBUMIN GENE

Cloned DNA containing the first 9 exons of the rat albumin gene was digested with EcoRI and HindIII, and the resulting fragments were used to screen for regions with relatively high affinity for protein. Of 3 restriction fragments preferentially bound, the fragment containing the first 2 exons of the albumin gene was consistently bound over others by heat-stable protein extracted from liver nuclei with 0.35-1.0 M NaCl. Proteins extracted with lower and higher ionic strength buffers bound the DNA fragments, but with little specificity. The DNA fragment that was preferentially bound consistently by the 1.0 M nuclear extract was subcloned into pBR325, and it was used to isolate the specific DNA-binding activity. After purification, histone H1 was the polypeptide with preferential DNA-binding activity. Histone H1 has a high-affinity binding site in the 5'' end of the rat albumin gene, within 440 5''-flanking base pairs and the first 2 exons of the gene.