Identification of cell cycle-regulated phosphorylation sites on nuclear lamin C.
The mechanism by which MPF induces nuclear lamin disassembly and nuclear envelope breakdown during mitosis was studied in a frog egg extract in which the transition from interphase to mitosis can be induced by the addition of MPF. Bacterially expressed human nuclear lamin C, assembled in vitro into filaments, showed increased phosphorylation on specific sites in the extract in response to MPF. Phosphorylation was accompanied by disassembly of the lamin filaments. We determined the sequences of the sites phosphorylated both in the presence and absence of MPF. The sequence data suggest that multiple protein kinases act on the lamins, and S6 kinase II was identified as one potentially important lamin kinase.
Ward
G E
GE
Department of Biochemistry and Biophysics, University of California, San Francisco 94143.
Kirschner
M W
MW
D000595:Amino Acid Sequence; D000818:Animals; D002453:Cell Cycle / Q000502:physiology*; D006133:Growth Substances / Q000502:physiology; D006801:Humans; D034904:Lamin Type A; D034882:Lamins; D007931:Leucyl Aminopeptidase; D016200:Maturation-Promoting Factor; D008938:Mitosis / Q000502:physiology; D008969:Molecular Sequence Data; D009685:Nuclear Envelope / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014982:Xenopus laevis / Q000378:metabolism
D006133:Growth Substances; D034904:Lamin Type A; D034882:Lamins; D009687:Nuclear Proteins; D010710:Phosphates; D011993:Recombinant Fusion Proteins; C440308:lamin C; D011494:Protein Kinases; D016200:Maturation-Promoting Factor; D007931:Leucyl Aminopeptidase