ARTTAGSYRRYRRRCCSPRRLYRLRRRRYRSSRRRRRRPCRRRRHRRVCRRVRRRRRCCRRR 62 Protamines substitute for histones in the chromatin of sperm during the haploid phase of spermatogenesis. They compact sperm DNA into a highly condensed, stable and inactive complex. Protamine 2a Sperm histone P2a ST2a PRM2_HORSE