SUBCELLULAR-DISTRIBUTION OF DISTINCT NUCLEOLIN SUBFRACTIONS RECOGNIZED BY 2 MONOCLONAL-ANTIBODIES

Monoclonal antibodies binding to different domains of nucleolin have b een used to localize nucleolin in tissue culture cells of Xenopus laev is. The monoclonal antibody b6-6E7 binds to an epitope in the N-termin al domain, which contains arrays of phosphorylation consensus sites. T his monoclonal antibody binds to nucleolin of oocytes and of eggs with high affinity. In contrast, the monoclonal antibody Nu-1H6 binds poor ly to the modified forms of nucleolin arising during meiosis and mitos is. In interphase cells, monoclonal antibody b6-6E7 preferentially sta ins the periphery of the nucleoli, where most of the rRNA accumulates. Staining by monoclonal antibody Nu-1H6 complements this pattern by st aining mainly the center of the nucleoli. The epitope of monoclonal an tibody Nu-1H6 is within the central domain of nucleolin, which contain s the first two RNA binding domains. RNase treatment of cells results in loss of nucleolin from nucleoli. In mitotic cells, both monoclonal antibodies decorate the surface of condensing chromosomes in prophase. The periphery of the condensed chromosomes in metaphase and anaphase is preferentially stained by monoclonal antibody b6-6E7. (C) 1998 Acad emic Press.