Abstract
We report here purification and characterization of chromosome condensation protein complexes (termed condensins) containing XCAP-C and XCAP-E, two Xenopus members of the SMC family. Sucrose density gradient centrifugation reveals two major forms of condensins. The 8S form is a heterodimer of XCAP-C and XCAP-E, whereas the 13S form contains three additional subunits. One of them is identified as a homolog of the Drosophila Barren protein whose mutation shows a defect in chromosome segregation. Chromosomal targeting of condensins is mitosis-specific and is independent of topoisomerase IIalpha. 13S condensin is required for condensation, as demonstrated by immunodepletion and rescue experiments. Our results suggest that the condensin complexes represent the most abundant structural components of mitotic chromosomes and play a central role in driving chromosome condensation.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adenosine Triphosphatases / chemistry
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Adenosine Triphosphatases / genetics
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Adenosine Triphosphatases / isolation & purification*
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Amino Acid Sequence
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Animals
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Antigens, Neoplasm
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Carrier Proteins / chemistry
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Carrier Proteins / genetics
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Carrier Proteins / isolation & purification*
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Cell Cycle
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Cell Cycle Proteins / chemistry
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / isolation & purification*
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Centrifugation, Density Gradient
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Chromosomal Proteins, Non-Histone / chemistry
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Chromosomal Proteins, Non-Histone / genetics
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Chromosomal Proteins, Non-Histone / isolation & purification*
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Chromosomes / chemistry
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DNA Topoisomerases, Type II* / metabolism
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DNA-Binding Proteins / chemistry
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / isolation & purification*
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Dimerization
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Drosophila
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Drosophila Proteins*
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Female
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Isoenzymes / metabolism
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Macromolecular Substances
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Mitosis
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Molecular Sequence Data
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Multiprotein Complexes
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Nuclear Proteins / chemistry
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Nuclear Proteins / genetics
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Nuclear Proteins / isolation & purification*
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Ovum / chemistry
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Phosphorylation
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Protein Conformation
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Sequence Homology, Amino Acid
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Species Specificity
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Xenopus
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Xenopus Proteins*
Substances
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Antigens, Neoplasm
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Barr protein, Drosophila
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Carrier Proteins
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Cell Cycle Proteins
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Chromosomal Proteins, Non-Histone
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DNA-Binding Proteins
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Drosophila Proteins
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Isoenzymes
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Macromolecular Substances
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Multiprotein Complexes
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NCAPH protein, human
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Nuclear Proteins
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SMC2 protein, human
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SMC4 protein, Xenopus
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XCAP-E protein, Xenopus
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Xenopus Proteins
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condensin complexes
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Adenosine Triphosphatases
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DNA Topoisomerases, Type II