組蛋白密碼

組蛋白密碼（Histone code）是一個描述真核生物藉修飾包裹DNA的組蛋白（主要是其N端尾）以調控基因表達的理論，和DNA甲基化共同組成表觀遺傳密碼（英語：epigenetic code）^[2] 。組蛋白上的修飾包括乙酰化、甲基化、磷酸化、泛素化、二磷酸腺苷核糖基化、GlcNAc糖基化（英語：GlcNAc）^[3]、瓜氨酸化、脯氨酸異構化（英語：Proline isomerization in epigenetics）^[4]與SUMO修飾（英語：SUMO protein）等^[5]，這些修飾的組合可影響染色體結構以及與其他蛋白的結合力，提升或降低基因的轉錄。人類細胞中組蛋白修飾的種類複雜，其中某幾種修飾可能傾向出現在同一個組蛋白上^[6]。近年由於質譜法技術的發展而有更多修飾種類與位點被發現^[7]，也有許多研究探討加上或移除組蛋白修飾的多種酵素，以及可辨認這些修飾而與之結合的其他蛋白^[8]。

已知的組蛋白修飾位點與種類^[1]

種類

組蛋白修飾對基因轉錄的影響

修飾種類	組蛋白位點
	H3K4	H3K9	H3K14	H3K27	H3K79	H3K36	H4K20	H2BK5	H2BK20
單甲基化	促進[9]	促進[10]		促進[10]	促進[10][11]		促進[10]	促進[10]
雙甲基化		抑制[12]		抑制[12]	促進[11]
三甲基化	促進[13]	抑制[10]		抑制[10]	促進[11] 抑制[10]	促進		抑制[12]
乙酰化	促進[14]	促進[13]	促進[13]	促進[15]					促進

參考文獻

• 分子與細胞生物學主題

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