PMID: 9005649Jan 1, 1996Paper

The dynamic intracellular distribution of nucleolar protein B23 in the interphase and mitotic cells of mammalian cultures

Tsitologiia
O V ZatsepinaI S Kudriavtsev

Abstract

Using monoclonal antibodies against B23 (Ochs et al., 1983) and indirect immunofluorescence of cells exposed to different conditions of fixation, distribution of B23 in HeLa (human) PtK1 (rat kangaroo) and PK (pig) cells was studied at interphase and mitosis. In different cells B23 is distributed in a similar manner. At interphase it is located mainly within nucleoli. When cells enter mitosis (at prophase), B23 translocates from nucleoli to the nucleoplasm, and after breakdown of the nuclear envelope at prometaphase-to the cytoplasm to remain there till the end of telophase. As extraction buffers are applied to remove soluble cytoplasmic proteins. B23 is clearly seen on the surface of chromosomes. This unequivocally indicates that B23 is a "chromosomal passenger protein" (Earnshaw, Barnet, 1991). At telophase, the formation of numerous prenucleolar bodies on the surface of chromosomes starts. A long-term incubation of cells with actinomycin D prevents from the appearance of B23 around chromosomes and within prenucleolar bodies.