▁human ▁is ▁available ▁which ▁is ▁located ▁at ▁the ▁end ▁of ▁the ▁largest ▁hist one ▁gene ▁cluster . ▁Currently ▁other ▁less ▁extens ively ▁studied ▁H 2 A ▁variants ▁are ▁starting ▁to ▁emer ge ▁such ▁as ▁H 2 A . J . ▁ ▁Vari ants ▁of ▁hist one ▁H 2 B ▁ ▁H 2 B ▁hist one ▁type ▁is ▁known ▁to ▁have ▁a ▁limited ▁number ▁of ▁variants ▁at ▁least ▁in ▁m amm als , ▁ap ic om plex a ▁and ▁sea ▁ur ch ins . ▁H 2 B . 1 ▁is ▁a ▁test is , ▁o ocy te ▁and ▁z yg ote ▁specific ▁variant ▁that ▁forms ▁sub n uc le os om al ▁particles , ▁at ▁least , ▁in ▁s per mat ids . ▁It ▁can ▁dim er ize ▁with ▁H 2 A . L ▁and ▁H 2 A . 1 . ▁H 2 B . W ▁is ▁involved ▁in ▁s per mat ogen esis , ▁tel om ere ▁associated ▁functions ▁in ▁s perm ▁and ▁is ▁found ▁in ▁s per mat ogen ic ▁cells . ▁It ▁is ▁character ized ▁by ▁the ▁extension ▁of ▁the ▁N - term inal ▁tail . ▁sub H 2 B ▁particip ates ▁in ▁reg ulation ▁of ▁s per mi ogen esis ▁and ▁is ▁found ▁in ▁non - n uc le os om al ▁particle ▁in ▁the ▁sub ac ros ome ▁of ▁s perm ato zo a . ▁This ▁variant ▁has ▁a ▁b ipart ite ▁nuclear ▁local ization ▁signal . ▁H 2 B . Z ▁is ▁an ▁ap ic om plex an