Counting Condensins on chromosomes

Locations of Condensins I and II on chromosomes during cell division
Locations of Condensins I and II (green) on chromosomes (magenta) during cell division IMAGE: EMBL/Nike Walther

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EMBL scientists count and locate chromosomal proteins during cell duplication

Chromosomes are highly organised, dense arrangements of DNA, which form every time our cells duplicate themselves. Two protein complexes, Condensin I and II, are known to help organise DNA strands into chromosomes during this process of mitosis, but it is unsure how. In a paper published in the Journal of Cell Biology, Jan Ellenberg and his group have measured how many Condensin proteins are bound to the chromosomes, during the different stages of mitosis, using quantitative live cell imaging. The proteins’ precise locations on the chromosome, as well as their spacing along the DNA strand was also identified by super-resolution imaging. Based on this research, Jan Ellenberg and his team propose that Condensins organise DNA into chromosomes by forming highly-regulated loops of DNA. This supports previous results published by the Haering group at EMBL and will further our understanding of how Condensins organise DNA during mitosis.