centromeric

Centromeric refers to the centromere, the primary constriction of a chromosome that plays a central role in chromosome segregation during cell division. In most eukaryotes, the centromere is defined not by a single DNA sequence but by specialized chromatin and by the presence of a histone H3 variant called CENP-A (Centromere Protein A) that replaces conventional histone H3 in centromeric nucleosomes.

Some organisms have point centromeres defined by a specific DNA sequence, while others have regional centromeres defined largely by epigenetic markers. The centromere serves as the foundation for the kinetochore, a protein complex that binds spindle microtubules and mediates chromosome movement during mitosis and meiosis. This process supports accurate sister chromatid separation and the proper distribution of genetic material to daughter cells.

Centromeric DNA often consists of highly repetitive sequences; in humans, alpha-satellite DNA forms large arrays at many centromeres, while pericentromeric regions are enriched in heterochromatin and other repeats. Centromeric identity is maintained epigenetically with CENP-A nucleosomes and other kinetochore proteins; neocentromeres can form at non-centromeric loci under certain circumstances, illustrating the extent to which centromere function is preserved beyond primary DNA sequence.

Evolutionary divergence of centromere sequences occurs rapidly, a phenomenon linked to centromere drive; despite sequence variation, centromeric function is conserved. Dysfunction or instability at centromeres can contribute to aneuploidy and cancer, making centromere biology a focus of cytogenetics, chromatin research, and cell biology.