An Unusual Group of Lysine‐Rich Histones from Gonads of a Sea Cucumber, Holothuria tubulosa

Gonads of the male Holothuria tubulosa contain two families of lysine‐rich histones. One of these families resembles the lysine‐rich histones found in somatic tissues of higher organisms ( e.g. calf and rabbit). The other family, which may be restricted to the male gonad, is recognizably related to the first family and yet is quite distinct. About 35% of the tryptic peptides differ between these families. These findings support the notion that a broad spectrum of structural variation may exist in lysine‐rich histones, perhaps even merging into structures of the slightly lysine‐rich class.