centromeres

Definition: Specialized chromosome region reacting to the spindle at nuclear division and to which spindle fibers attach during cell division. Appears as a distinct "waist" by microscopy. In a few organisms the centromeric properties are distributed over the entire length of the chromosome (diffuse centromere).

The term introduced by Darlington (1936) for the specialized chromosome region which reacts to the spindle at nuclear division and to which spindle fibers attach during cell division. Appears as a distinct "waist" by microscopy. In a few organisms the centromeric properties are distributed over the entire length of the chromosome (diffuse centromere).

At each mitosis, accurate segregation of every chromosome is ensured by the assembly of a kinetochore at each centromeric locus.

Six foundation kinetochore proteins that assemble hierarchically and co-dependently have been identified in vertebrates. CENP-A, Mis12, CENP-C, CENP-H and CENP-I localize to a core domain of centromeric chromatin. The sixth protein, CENP-B, although not essential in higher eukaryotes, has homologues in fission yeast that bind pericentric DNA and are essential for heterochromatin formation.

Foundation kinetochore proteins have various roles and mutual interactions, and their associations with centromeric DNA and heterochromatin create structural domains that support the different functions of the centromere.

See also

 mitosis
 kinetochore
 CENPs

References

 Henikoff S, Dalal Y. Centromeric chromatin: what makes it unique? Curr Opin Genet Dev. 2005 Apr;15(2):177-84. PMID: 15797200

 Amor DJ, Kalitsis P, Sumer H, Choo KH. Building the centromere: from foundation proteins to 3D organization. Trends Cell Biol. 2004 Jul;14(7):359-68. PMID: 15246429

 Maly IV, Borisy GG. Self-organization of treadmilling microtubules into a polar array. Trends Cell Biol. 2002 Oct;12(10):462-5. PMID: 12441249

 Bernard P, Allshire R. Centromeres become unstuck without heterochromatin. Trends Cell Biol. 2002 Sep;12(9):419-24.
PMID: 12220862

 Eichler EE. Repetitive conundrums of centromere structure and function. Hum Mol Genet. 1999 Feb;8(2):151-5. PMID: 9931322

 Dej KJ, Orr-Weaver TL. Separation anxiety at the centromere. Trends Cell Biol. 2000 Sep;10(9):392-9. PMID: 10932097

 Choo KH. Centromerization. Trends Cell Biol. 2000 May;10(5):182-8. PMID: 10754560