Here, we describe the cloning and characterization of ScII, the second most abundant protein after topoisomerase II, of the chromosome scaffold fraction to be identified. ScII is structurally related to a protein, Smc1p, previously found to be required for accurate chromosome segregation in Saccharomyces cerevisiae. ScII and the other members of the emerging family of SMC1-like proteins are likely to be novel ATPases, with NTP-binding A and B sites separated by two lengthy regions predicted to form an alpha-helical coiled-coil. Analysis of the ScII B site predicted that ScII might use ATP by a mechanism similar to the bacterial recN DNA repair and recombination enzyme. ScII is a mitosis-specific scaffold protein that colocalizes with topoisomerase II in mitotic chromosomes. However, ScII appears not to be associated with the interphase nuclear matrix. ScII might thus play a role in mitotic processes such as chromosome condensation or sister chromatid disjunction, both of which have been previously shown to involve topoisomerase II.
ScII: an abundant chromosome scaffold protein is a member of a family of putative ATPases with an unusual predicted tertiary structure.
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N Saitoh, I G Goldberg, E R Wood, W C Earnshaw; ScII: an abundant chromosome scaffold protein is a member of a family of putative ATPases with an unusual predicted tertiary structure.. J Cell Biol 15 October 1994; 127 (2): 303–318. doi: https://doi.org/10.1083/jcb.127.2.303
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