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#CENP-A

2 public questions tagged with this topic.

Nucleosome Packing

CENP-A mainly localizes to:

CENP-A containing nucleosomes localize almost exclusively to functional centromere, not dispersed throughout chromosome arms. High resolution immunofluorescence and chromatin immunoprecipitation sequencing show discrete foci at primary constriction colocalizing with inner kinetochore markers CENP-C and CENP-T during interphase and mitosis. At centromere CENP-A directly recruits CCAN network initiating kinetochore assembly ensuring spindle microtubule attachment and checkpoint signaling. It does not accumulate at telomeres containing TTAGGG repeats protected by shelterin, nor at nucleolar organizer regions containing rDNA, nor at replication origins firing genome wide.

Ref: Earnshaw and Migeon CENP-A Localization; Lodish et al., Chapter 19: CENP-A Mainly Localizes to Centromere

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Nucleosome Packing

CENP-A is a variant of histone:

Centromeric chromatin contains distinctive histone variant CENP-A that epigenetically specifies centromere location independent of underlying DNA sequence in most eukaryotes. CENP-A resembles canonical histone H3 in histone fold domain sharing about sixty percent similarity, but possesses divergent N-terminus and loop1 centromere targeting domain CATD directing specific deposition via HJURP chaperone during G1. It replaces H3 in subset of nucleosomes at active centromere creating specialized octamer recruiting inner kinetochore. H1 is linker histone, H2A variants include H2A.Z, H4 lacks centromeric-specific variant analogous to CENP-A functionally.

Ref: Palmer et al., 1987 PNAS; Alberts et al., Molecular Biology of the Cell, Chapter 4: CENP-A is Variant of H3

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