Practice question

Histone H3 phosphorylation predominantly targets serine and threonine in the disordered N-tail, introducing negative phosphate that alters chromatin binding. Serine 10, adjacent to lysine 9, is phosphorylated by Aurora B kinase during early mitosis starting at pericentric heterochromatin and spreading along chromosomes, promoting condensation, release of HP1 and recruitment of condensin complexes. Outside mitosis, MSK1/2 phosphorylates the same residue upon growth factor signaling, facilitating transcription of immediate-early genes through协同 acetylation at K14. Detection of phospho-H3S10 serves as standard mitotic index marker.