Lysine-specific demethylase 9 (Round spermatid basic protein 1, RSBN1 or Rosbin) is a homeobox-like protein that is located in the nucleus and is expressed exclusively in haploid round spermatids. It modulates chromosome architecture by demethylating dimethylated 'Lys-20' of histone H4 (H4K20me2) [].This entry also includes dosage compensation protein dpy-21 from C. elegans. Dpy-21 is required for X chromosome dosage compensation by reducing X-linked gene transcription in hermaphrodites throughout development [, , , , , ].
