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{{protein
| Name = 真核起始因子4A-1
| caption =
| image =
| width = 250px
| HGNCid =
| Symbol = eIF4A-1
| AltSymbols =
| EntrezGene = 1973
| OMIM = 602641
| RefSeq = NP_001407
| UniProt = P60842
| PDB =
| ECnumber = 3.6.1.-
| Chromosome = 17
| Arm =
| Band =
| LocusSupplementaryData =
}}
{{protein
| Name = 真核起始因子4A-2
| caption =
| image =
| width = 250px
| HGNCid =
| Symbol = eIF4A-2
| AltSymbols =
| EntrezGene = 1974
| OMIM = 601102
| RefSeq = NP_001958
| UniProt = Q14240
| PDB =
| ECnumber = 3.6.1.-
| Chromosome = 3
| Arm =
| Band =
| LocusSupplementaryData =
}}
{{protein
| Name = 真核起始因子4A-3
| caption = 人类eIF4A-3的晶体结构
| image = 2hxy bio r 250.jpg
| width = 250px
| HGNCid =
| Symbol = eIF4A-3
| AltSymbols =
| EntrezGene = 9775
| OMIM = 608546
| RefSeq = NP_055555
| UniProt = P38919
| PDB = 2hxy
| ECnumber = 3.6.1.-
| Chromosome = 17
| Arm =
| Band =
| LocusSupplementaryData =
}}
'''[[真核起始因子]]4A'''（{{langx|en|'''e'''ukaryotic translation '''I'''nitiation '''F'''actor 4A}}，简称为'''eIF4A'''）是一种[[三磷酸腺苷|ATP]]依赖性[[RNA]]结合蛋白，一种RNA依赖性[[ATP酶]]，和一种RNA[[解旋酶]]，它在[[真核翻译]]起始进程中发挥重要作用。它被认为可以解开[[mRNA]]的[[5'端]]非翻译区的二级和三级结构，以使[[核糖体]]的附着更容易，同时允许核糖体进行[[密码子|起始密码子]]扫描。<ref>{{en}}{{cite journal en|author=Hernández G, Vazquez-Pianzola P|title=Functional diversity of the eukaryotic translation initiation factors belonging to eIF4 families|journal=Mech Dev|volume=122|year=2005|pages=865-76|pmid=15922571}}</ref>

eIF4A在人体中有三个亚型：eIF4A-1、eIF4A-2和eIF4A-3。

== 结构 ==
eIF4A是[[DEAD盒]]RNA解旋酶超家族成员，其[[氨基酸]]序列中具有8个保守区，保守区内含有一致的特殊序列。已知的解旋酶结构具有两个[[结构域]]：RNA结合结构域和ATP酶结构域；保守区，包括ATP结合位点，线性排列在两个结构域之间的裂缝中。[[酵母]]的eIF4A（缺少RNA结合结构域）的[[N端]]ATP酶结构域包含一个七个β链组成的扭曲的[[β折叠]]片，其两侧分别有4个和5个[[α螺旋]]。<ref>{{en}}{{cite journal en|author=Benz J, Trachsel H, Baumann U|title=Crystal structure of the ATPase domain of translation initiation factor 4A from Saccharomyces cerevisiae--the prototype of the DEAD box protein family|journal=Structure|volume=15|year=1999|pages=671-9|pmid=10404596}}</ref>而最近对人类eIF4A的结构研究发现，eIF4A的两个结构域都为α/β型折叠，且在结合RNA前后发生了构象变化。<ref>{{en}}{{cite journal en|author=Andersen CB, Ballut L, Johansen JS, Chamieh H, Nielsen KH, Oliveira CL, Pedersen JS, Séraphin B, Le Hir H, Andersen GR|title=Structure of the exon junction core complex with a trapped DEAD-box ATPase bound to RNA|url=https://archive.org/details/sim_science_2006-09-29_313_5795/page/1968|journal=Science|volume=313|year=2006|pages=1968-72|pmid=16931718}}</ref>

== 功能 ==
eIF4A的解旋功能可能是因为ATP结合和[[水解]]引起蛋白质结构变化和RNA亲合性的变化。虽然如此，单独存在的eIF4A只是一种低效的解旋酶，因为它从单链RNA上脱离的速率远大于水解ATP的速率。而eIF4A的解旋酶活性可被[[eIF4B]]，[[eIF4H]]和[[eIF4F]]增强。现在还不清楚这些因子是否或如何通过与eIF4A的相互作用改变了[[酶动力学|酶的动力学参数]]，例如通过增强它与RNA的亲合性从而带来活性的提高。

在真核生物中，eIF4A可以以自由形式存在或者作为[[eIF4F]]的一部分。在[[哺乳动物]]中eIF4A是结合[[eIF4G]]的两个位点上，在酵母中结合在eIF4G的一个单独位点上。<ref>{{en}}{{cite journal en|author=Imataka H, Sonenberg N|title=Human eukaryotic translation initiation factor 4G (eIF4G) possesses two separate and independent binding sites for eIF4A|url=https://archive.org/details/sim_molecular-and-cellular-biology_1997-12_17_12/page/6940|journal=Mol Cell Biol|volume=17|year=1997|pages=6940-7|pmid=9372926}}</ref>它同样可结合[[翻译 (遗传学)|翻译]]调控因子[[p97]]和[[PABP]]作用蛋白（PABP-interacting protein，PAIP）。

== 参考文献 ==
{{reflist}}

== 参见 ==
*[[真核起始因子]]
*[[eIF4F]]中另外两个[[蛋白质亚基|亚基]]：
**[[eIF4E]]
**[[eIF4G]]

{{遗传学·翻译}}

[[Category:真核生物基因]]

EIF4A - 版本历史

imported>InternetArchiveBot：​Add 1 book for verifiability (20251017sim)) #IABot (v2.0.9.5) (GreenC bot

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