An approach to searching for specific proteins associated with active genes in hen oviduct

This study has examined an approach to searching for specific proteins associated with the altered nucleosome structure of transcriptionally active genes that are induced by steroid hormones in the hen oviduct. Hen oviduct nuclei were digested with micrococcal nuclease by the procedure which selectively excises nucleosomes from the ovalbumin gene. The oviduct nuclei, as well as chick erythrocyte nuclei, were also digested with DNAase I under conditions preferentially sensitive to the ovalbumin gene, as well as the globin gene. Released proteins were characterized by one- and two-dimensional polyacrylamide gel electrophoresis with detection by silver staining. Thus, high mobility group (HMG) proteins 14 and 17 were found in the three cases of nuclease digestion. Furthermore, about 10, 20 and 15 nonhistone protein spots, specific to each nuclease action, were observed in the cases of micrococcal nuclease to oviduct nuclei and DNAase I to oviduct and erythrocyte nuclei, respectively. Between these three series of protein spots, at least three spots were characterized to be common to those released by both nucleases from oviduct nuclei. These common proteins may be involved, as estrogen receptor proteins or others, in recognition of the ovalbumin DNA sequences, followed by a non-sequence-specific process in which the HMG proteins alter the structure of nucleosomes along the transcription unit.