楊政哲 asked in 科學植物學 · 1 decade ago

核小體nucleosome中tail-bridging效應?

核小體nucleosome中tail-bridging效應?

請對tail-bridging effect作詳細解釋

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  • Anonymous
    1 decade ago
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    ★版主,各位朋友好:

    請容在下分享一點小小的淺見。

    The nucleosome tail bridging effect 其實是 histone tail modifications 其中之一的現象。

    沒有很難。

    引述,

    『 Histone tail modifications might affect nucleosome stability. 』

    來看Nature 舉例的圖:reference(ref.)

    圖片參考:http://www.nature.com/nrg/journal/v9/n1/images/nrg...

    看 b.的右邊,

    『 A heterochromatin protein 1 (HP1) dimer that binds to two histone H3 tails

    that are methylated at lysine 9 (H3K9) might bridge two tails on the same nucleosome

    or on two nearby nucleosomes and reduce mobility,

    thus preventing nucleosome eviction. 』

    所以,

    原本大量攜帶正電的histone(because of Lys, His, etc.),

    經過methylation去除電性,蛋白質(如HP1),

    可以整個做穩定的packing,以利形成heterochromatin。

    整個nucleosome,藉由histone tail的修飾( histone tail modifications ),

    可以調控整個基因的表現。

    整個機制是動態的,可以用Nucleosome Dynamics 來形容之。ref.

    引述,

    『 The bridging of tails to negative charges on neighbouring nucleosomes leads to attraction that can be regulated via the amount of charges on the tails – that is under biochemical control. 』

    結論,

    請搜尋 histone tail modifications,資料龐雜不贅述。

    觀念是,

    帶正電的histone和帶負電的DNA,

    彼此利用methylation,和acetylation來動態調控彼此纏繞的鬆,緊,

    來開啟,或關閉基因表現(gene expression)。

    尾巴架橋(tail bridging),固定histone,nucleosome呈現stable state,

    形成heterochromatin,基因表現關閉,利於染色質移動等等。

    ref.

    <Controlled DNA compaction within chromatin:The tail-bridging effect>

    ref.

    <Nature Trans-tail histone modifications: wedge or bridge?>

    ref.

    <Interactions between isolated nucleosome core particles: A tail-bridging effect? >

    粗淺回答僅供參考,

    比喻不當請包涵,

    文字內容有誤請專家高手不吝指正,

    也歡迎互動討論。

    Google關鍵字,皆已附在文中。

    藍色反白有參考網址。

    網頁內容所有權皆屬原作。

    避免圖變叉燒,行距跑掉,

    請儘量用FireFox瀏覽。

    2009-04-30 00:28:22 補充:

    感謝版主大人雅量,各位前輩贊點,批評指教。

    後學會日益精進,都是因為各位大師的指導。

    感恩!

    祝福各位。

    Source(s): 上班還摸魚之小常識,Google姊姊,......量繁不及備書
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