Characterization of a novel 350-kilodalton nuclear phosphoprotein that is specifically involved in mitotic-phase progression

Mol Cell Biol. 1995 Sep;15(9):5017-29. doi: 10.1128/MCB.15.9.5017.


A gene assigned to human chromosome 1q32-41 encodes a novel protein of 3,113 amino acids containing an internal tandem repeat of 177 amino acids. The protein, which we have named "mitosin," was identified by direct binding to purified retinoblastoma protein in vitro with a region distantly related to the retinoblastoma protein-binding site of E2F-1. Mitosin is expressed throughout S, G2, and M phases of the cell cycle but is absent in G1. Its localization is dramatically reorganized from a rather homogeneous nuclear distribution in S phase to paired dots at the kinetochore/centromere region, to the spindle apparatus, and then to the midbody during M-phase progression. This spatial reorganization coincides closely with the temporal phosphorylation patterns of mitosin. Overexpression of N-terminally truncated mutants blocks cell cycle progression mainly at G2/M. These results suggest that mitosin may play an important role in mitotic-phase progression.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Carrier Proteins*
  • Cell Compartmentation
  • Cell Cycle Proteins*
  • Centromere / chemistry
  • Chromosomal Proteins, Non-Histone*
  • Chromosome Mapping
  • Chromosomes, Human, Pair 1 / genetics*
  • Cloning, Molecular
  • DNA-Binding Proteins*
  • E2F Transcription Factors
  • E2F1 Transcription Factor
  • Fluorescent Antibody Technique
  • Humans
  • Microfilament Proteins
  • Mitosis / genetics*
  • Molecular Sequence Data
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / metabolism
  • Peptide Fragments / metabolism
  • Phosphoproteins / genetics*
  • Phosphoproteins / metabolism
  • Phosphorylation
  • Protein Binding
  • Recombinant Fusion Proteins / metabolism
  • Retinoblastoma Protein / metabolism
  • Retinoblastoma-Binding Protein 1
  • Sequence Analysis, DNA
  • Spindle Apparatus / chemistry
  • Transcription Factor DP1
  • Transcription Factors / metabolism


  • Carrier Proteins
  • Cell Cycle Proteins
  • Chromosomal Proteins, Non-Histone
  • DNA-Binding Proteins
  • E2F Transcription Factors
  • E2F1 Transcription Factor
  • E2F1 protein, human
  • Microfilament Proteins
  • Nuclear Proteins
  • Peptide Fragments
  • Phosphoproteins
  • Recombinant Fusion Proteins
  • Retinoblastoma Protein
  • Retinoblastoma-Binding Protein 1
  • Transcription Factor DP1
  • Transcription Factors
  • centromere protein F

Associated data

  • GENBANK/U30872