The C terminus of mitosin is essential for its nuclear localization, centromere/kinetochore targeting, and dimerization.
Mitosin is a novel 350-kDa nuclear phosphoprotein that dramatically relocates from the evenly nuclear distribution in S phase to the centromere/kinetochore and mitotic apparatus in M phase. The dynamic relocalization of mitosin is accompanied by the phosphorylation of itself, suggesting that mitosin plays a role in mitotic progression. The molecular basis of nuclear localization and targeting of mitosin to the centromere/kinetochore were characterized using a set of epitope-tagged deletion mutants. The data indicate that the extreme C terminus (amino acids 2,487-3,113) of mitosin has both an independent centromere/kinetochore targeting domain and an unusually spaced bipartite nuclear localization signal. Moreover, the same centromere/kinetochore targeting domain was shown to be essential for the ability of mitosin to bind to itself or other putative mitosin-associated proteins through use of the yeast two-hybrid system. These results suggest that the C terminus of the mitosin is essential for its role in influencing cell cycle progression.
Zhu
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X
Center for Molecular Medicine/Institute of Biotechnology, University of Texas Health Science Center at San Antonio 78245, USA.
Chang
K H
KH
He
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D
Mancini
M A
MA
Brinkley
W R
WR
Lee
W H
WH
D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D001704:Biopolymers; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D002503:Centromere / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone; D006367:HeLa Cells; D006801:Humans; D018386:Kinetochores / Q000378:metabolism*; D051379:Mice; D008840:Microfilament Proteins; D016253:Microscopy, Immunoelectron; D008938:Mitosis; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction
D001704:Biopolymers; D002868:Chromosomal Proteins, Non-Histone; D008840:Microfilament Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; C094772:centromere protein F