IDENTIFICATION, NUCLEAR-LOCALIZATION, AND BINDING ACTIVITIES OF OZF -A HUMAN PROTEIN SOLELY COMPOSED OF ZINC-FINGER MOTIFS

The OZF cDNA was identified in a human mammary cell line and encodes a polypeptide solely composed of ten zinc-finger motifs which belongs t o the Kruppel family of zinc-finger proteins. The OZF protein produced in Escherichia coli binds zinc ions, DNA and heparin. These binding a ctivities are characteristic of zinc-finger proteins. Immunochemical a nalysis using antibodies produced against the recombinant protein dete cted its expression in human mammary epithelial cells but not in strom a cells, which is consistent with the pattern of expression observed a t the RNA level in cell cultures. Western blot analysis demonstrated t he expression of a 33-kDa nuclear protein similar in size to the predi cted protein and therefore excluded the presence of an additional tran s-acting domain. These data establish the unique structure of the OZF protein which is distinct from previously identified zinc-finger prote ins. In addition, OZF protein overexpression was found in a tumor cell line, which suggests a possible involvement in carcinogenesis.