We have examined the role of protein phosphatase type 1 (PP-1) in mammalian cell mitosis. Immunofluorescence using anti-PP-1 antibodies revealed that PP-1, which is mainly localized in the cytoplasm of G1 and S phase cells, accumulates in the nucleus during G2 phase and intensely colocalizes with individual chromosomes at mitosis. This increase in nuclear PP-1 in G2/M cells was confirmed by immunoblotting on subcellular fractions. Microinjection of neutralizing anti-PP-1 antibodies before division blocked cells at metaphase, whereas injection of PP-1 in one pole of an anaphase B cell accelerated cytokinesis and the reflattening of the injected cell. These results reveal a specific cell cycle-dependent redistribution of PP-1 and its involvement in reversing p34cdc2-induced effects after mid-mitosis in mammalian cells.
Protein phosphatase type 1 in mammalian cell mitosis: chromosomal localization and involvement in mitotic exit.
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A Fernandez, D L Brautigan, N J Lamb; Protein phosphatase type 1 in mammalian cell mitosis: chromosomal localization and involvement in mitotic exit.. J Cell Biol 15 March 1992; 116 (6): 1421–1430. doi: https://doi.org/10.1083/jcb.116.6.1421
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