A NOVEL CELL-CYCLE-DEPENDENT 350-KDA NUCLEAR-PROTEIN - C-TERMINAL DOMAIN SUFFICIENT FOR NUCLEAR-LOCALIZATION

We have screened human scleroderma patients for immunoreactivity with the components of the nucleus and the mitotic apparatus. We announce t he identification of a novel cell-cycle-dependent nuclear protein usin g serum from a CREST patient AH. AH protein first appears at the nucle us of G2-phase and associates with the centrosome throughout the cell cycle. As chromosomes condense during the prophase, AH protein becomes enriched at the kinetochores. During mitosis, AH protein progressivel y disperses from the kinetochore and becomes diffusely localized in th e cytoplasm and in telophase; it appears to be enriched within the int racellular bridge. Molecular cloning and transfection studies reveal t hat the 350-kDa AH protein contains a coiled-coil and a globular domai n at the C-terminus that is sufficient for nuclear localization. (C) 1 995 Academic Press, Inc.