Histone variants Flashcards
H3.3?
A variant of H3 with only 4aa difference. However, this 4aa difference is evolutionarily conserved. Present in both active genes and constitutive heterochromatin
CenH3?
aka CENP-A. Present specifically in centrosomal chromatin.
What are two H3 veriants
H3.3 and CenH3
(gamma)H2AX
recruited at DSBs. gamma means phosphorylated
When are new H2AX recruited to chromatin?
gamma-H2AX can be
added at any time during the cell cycle as DSB can happen at anytime not just S phase
H2A.Z?
active promoters. H2A.Z wraps DNA more tightly, which will have
consequences on how gene transcription will proceed. In plants for example, its loading onto chromatin is somewhat
temperature-dependent.
mH2A?
macroH2A. Only present in vertebrates. It has 200aa more than the regular H2A, and is
enriched on the inactive X chromosome. (m = mommy)
H2A.B?
It is deposited at sites where
active transcription, splicing, etc are happening, but only in testis cells. (B = balls)