Cip1 Interacting Zinc Finger Protein (CIZ1)

The deduced 898-amino acid protein contains 2 glutamine-rich domains, 3 C2H2-type zinc finger motifs, an acidic domain, and a C-terminal matrin (MATR3)-homologous domain 3 (MH3). Northern blot analysis detected CIZ1 in most human cell lines and mouse tissues examined, with highest expression in mouse testis and kidney. Western blot analysis detected proteins of 120 and 95 kD in most tissues. In a human osteosarcoma cell line, the 95-kD form predominated in detergent extracts and the 120-kD form was present in detergent-resistant cell nuclei. CIZ1 was detected at high levels in ependymomas, medulloblastomas, and gliomas. CIZ1 localized in the nucleus of transfected COS-7 cells in 2 patterns: a diffuse pattern that excluded nucleoli and a punctate pattern where CIZ1 colocalized with DNA.