To adapt to various states of chromatin, corresponding histone variants are incorporated in nucleosome, and certain modifications also occur on the variants tails. 对于不同状态的染色质，核小体中会组装人相应的组蛋白变体，并且各种组蛋白变体的尾部也能发生多种修饰。
But enough evidence has accumulated to prove that some proteins can in fact copy themselves and that variants of PrP are essential players in spongiform encephalopathies. 但是充足的证据证明，某些蛋白质的确可以自我复制，且普恩蛋白变体在海绵状脑病上扮演了重要角色。
