The SMC proteins and the coming of age of the chromosome scaffold hypothesis.
The mechanism of chromosome condensation is one of the classic mysteries of mitosis. A number of years ago, it was suggested that nonhistone proteins of the chromosome scaffold fraction might help chromosomes to condense, possibly by constructing a framework for the condensed structure. Recent results have shown that topoisomerase II and the SMC proteins, two abundant members of the scaffold fraction, are required for chromosome condensation and segregation during mitosis. Topoisomerase II is a well-characterized enzyme. In contrast, nothing is yet known about the function of the SMC proteins. We summarize evidence suggesting that these proteins may be enzymes whose activity is somehow involved in the establishment and maintenance of mitotic chromosome morphology.
Saitoh
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Department of Cell Biology and Anatomy, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Goldberg
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Earnshaw
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WC
D000818:Animals; D030161:Avian Proteins; D017173:Caenorhabditis elegans / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins / Q000502:physiology; D018797:Cell Cycle Proteins / Q000502:physiology; D002868:Chromosomal Proteins, Non-Histone / Q000145:classification / Q000235:genetics / Q000502:physiology*; D002875:Chromosomes / Q000737:chemistry / Q000648:ultrastructure*; D015825:Chromosomes, Fungal / Q000737:chemistry / Q000648:ultrastructure; D004250:DNA Topoisomerases, Type II / Q000502:physiology; D004268:DNA-Binding Proteins / Q000502:physiology; D005656:Fungal Proteins / Q000502:physiology; D015801:Helminth Proteins / Q000502:physiology; D008938:Mitosis; D008954:Models, Biological; D005810:Multigene Family; D009687:Nuclear Proteins / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000378:metabolism; D000098550:Structural Maintenance of Chromosome Protein 1
D030161:Avian Proteins; D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; C090454:DPY-27 protein, C elegans; D005656:Fungal Proteins; D015801:Helminth Proteins; C109974:NCAPH protein, human; D009687:Nuclear Proteins; C090455:SMC2 protein, S cerevisiae; C490381:SMC2 protein, human; C090452:SMC4 protein, Xenopus; D029701:Saccharomyces cerevisiae Proteins; C089784:ScII protein, Gallus gallus; C090453:XCAP-E protein, Xenopus; D029867:Xenopus Proteins; D000098550:Structural Maintenance of Chromosome Protein 1; D004250:DNA Topoisomerases, Type II