DEAD box為一蛋白質家族的通稱,在原核生物真核生物細胞中皆有,因其中一個結構域有一天門冬胺酸-麩胺酸-丙胺酸-天門冬胺酸(DEAD)的氨基酸序列而得名[2]。此家族的蛋白多參與RNA相關反應[3],有許多蛋白為RNA解旋酶[4],可以消耗ATP的機制將雙股RNA解開[5]

DEAD/DEAH box RNA解旋酶
釀酒酵母的eIF4A結構(1qva[1]
鑑定
標誌DEAD
PfamPF00270旧版
Pfam宗系CL0023旧版
InterPro英语InterProIPR011545
PROSITE英语PROSITEPDOC00039
SCOP英语Structural Classification of Proteins1qva / SUPFAM
CDD英语Conserved Domain Databasecd00268

DEAH家族與SKI2家族的蛋白序列也與DEAD box家族的蛋白相似[6][7][8],三者合稱DExD/H家族蛋白[9]

結構

编辑

1980年代晚期有學者發現許多蛋白的NTP結合位點英语NTP binding site序列和eIF4ARNA解旋酶的相似[10],後續研究發現這些蛋白均有9個保守的結構域,由N端C端分別為Q結構域、結構域I、結構域Ia、結構域Ib、結構域II、結構域III、結構域IV、結構域V與結構域VI,其中結構域II又名沃克結構域-B英语Walker motifs,包含天門冬胺酸-麩胺酸-丙胺酸-天門冬胺酸(DEAD)的氨基酸序列[2]。Q結構域、結構域I、結構域II與結構域VI為結合與水解ATP所需,結構域Ia、結構域Ib、結構域III、結構域IV與結構域V則為結合RNA所需[11]

功能

编辑
 
mRNA剪接過程,其中標註為橘色的蛋白皆屬DEAD box家族

DEAD box家族的蛋白多為RNA解旋酶,參與轉錄RNA剪接核糖體組裝英语ribosome biogenesis、RNA轉運、轉譯與RNA降解等細胞中的多種RNA相關反應[9][12][13]

釀酒酵母mRNA剪接的過程有Sub2、Prp28與Prp5等3種DEAD box蛋白參與[5],其中Prp5可與U2 SnRNA英语U2 spliceosomal RNA結合以影響其結構,使其得以與mRNA內含子中的分支位點(branchpoint)結合[14];Prp28可能可識別內含子的5′端切割位點,但此蛋白無解旋酶活性[15]。另外Prp2、Prp16、Prp22、Prp43與Brr213等多種DEAH家族蛋白也參與mRNA剪切[16]

轉譯起始因子eIF4A為一DEAD box蛋白,在轉譯起始時可解開mRNA5′ UTR二級結構,以利核糖體小次單元掃描mRNA以尋找起始密碼子[17]。另一DEAD box Ded1也參與轉譯起始過程,但具體機制仍不明[18];還有一與Ded1相似的DEAD box蛋白Vasa可與eIF2互動[19]

參考文獻

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  1. ^ Johnson, E. R.; McKay, D. B. Crystallographic structure of the amino terminal domain of yeast initiation factor 4A, a representative DEAD-box RNA helicase. RNA. 1999, 5 (12): 1526–1534. PMC 1369875 . PMID 10606264. doi:10.1017/S1355838299991410. 
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  10. ^ Gorbalenya AE, Koonin EV, Donchenko AP, Blinov VM. Two related superfamilies of putative helicases involved in replication, recombination, repair and expression of DNA and RNA genomes. Nucleic Acids Res. June 1989, 17 (12): 4713–30. PMC 318027 . PMID 2546125. doi:10.1093/nar/17.12.4713. 
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