A heterodimeric coiled-coil protein required for mitotic chromosome condensation in vitro.
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.
Department of Pharmacology, University of California, San Francisco 94143-0450.
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Mitchison
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D002451:Cell Compartmentation; D018797:Cell Cycle Proteins; D002474:Cell-Free System; D002478:Cells, Cultured; D002868:Chromosomal Proteins, Non-Histone; D002875:Chromosomes / Q000502:physiology*; D003001:Cloning, Molecular; D005455:Fluorescent Antibody Technique; D008938:Mitosis / Q000502:physiology*; D008969:Molecular Sequence Data; D009024:Morphogenesis; D009068:Movement / Q000502:physiology; D009687:Nuclear Proteins / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D010063:Ovum / Q000502:physiology; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000276:immunology / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014981:Xenopus; D029867:Xenopus Proteins
D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; C109974:NCAPH protein, human; D009687:Nuclear Proteins; D011994:Recombinant Proteins; C490381:SMC2 protein, human; C090452:SMC4 protein, Xenopus; C090453:XCAP-E protein, Xenopus; D029867:Xenopus Proteins