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chromosomal radial array or rosette
There are 5 levels of folding of DNA in eukaryotic chromosomes. The radial array represents the 4th level of DNA folding. Nucleosomes (1st level of folding) are organized into solenoids (2nd level of folding). The solenoids in turn are folded into loops (3rd level of folding), which in turn form 6 loop rosette structures of 300 Kbp also known as radial arrays (4th level of folding). Topoisomerase 2 is found along DNA with a periodicity of 300 Kbp & is thought to be associated with formation of radial array structures. The radial arrays further fold into coils which form chromatid fibers (250 X 700 nm) which form the chromosomal banding seen on chromosomal staining.
General
DNA motif
macromolecular complex
Properties
SIZE: entity length = 300 KB/TURN
WIDTH = 250 NM
HEIGHT = 60 NM
COMPARTMENT: cell nucleus
References
- Manuelidis L.
A view of interphase chromosomes.
Science. 1990 Dec 14;250(4987):1533-40. Review.
PMID: 2274784
- Filipski J, Leblanc J, Youdale T, Sikorska M, Walker PR.
Periodicity of DNA folding in higher order chromatin structures.
EMBO J. 1990 Apr;9(4):1319-27.
PMID: 2323342
Component-of
chromosomal G-band
Components
chromosomal-loop