A Heterodimeric Coiled-Coil Protein Required for Mitotic Chromosome Condensation in Vitro

Cell. 1994 Nov 4;79(3):449-58. doi: 10.1016/0092-8674(94)90254-2.


We report here a chromosomal protein that plays an essential role in mitotic chromosome condensation in Xenopus egg extracts. Two polypeptides, designated XCAP-C and XCAP-E, were found to associate with each other in the extracts, presumably forming a heterodimer. During chromosome assembly in mitotic extracts, XCAP-C/E was recruited to the chromatin and formed a discrete internal structure within assembled chromosomes. Antibody blocking experiments showed that XCAP-C function is required for both assembly and structural maintenance of mitotic chromosomes in vitro. Deduced amino acid sequences revealed that the two polypeptides share common structural motifs, consisting of an N-terminal NTP-binding domain, two central coiled-coil regions, and a C-terminal conserved domain. These motifs are highly conserved in a protein family, members of which have been identified recently in both prokaryotes and eukaryotes.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Carrier Proteins / genetics
  • Carrier Proteins / immunology
  • Carrier Proteins / physiology*
  • Cell Compartmentation
  • Cell Cycle Proteins*
  • Cell-Free System
  • Cells, Cultured
  • Chromosomal Proteins, Non-Histone*
  • Chromosomes / physiology*
  • Cloning, Molecular
  • Fluorescent Antibody Technique
  • Mitosis / physiology*
  • Molecular Sequence Data
  • Morphogenesis
  • Movement / physiology
  • Nuclear Proteins / genetics
  • Nuclear Proteins / immunology
  • Nuclear Proteins / physiology*
  • Ovum / physiology
  • Protein Binding
  • Protein Structure, Secondary*
  • Recombinant Proteins / immunology
  • Recombinant Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Xenopus
  • Xenopus Proteins*


  • Carrier Proteins
  • Cell Cycle Proteins
  • Chromosomal Proteins, Non-Histone
  • NCAPH protein, human
  • Nuclear Proteins
  • Recombinant Proteins
  • SMC2 protein, human
  • SMC4 protein, Xenopus
  • XCAP-E protein, Xenopus
  • Xenopus Proteins

Associated data

  • GENBANK/U13673
  • GENBANK/U13674