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Nature 465: 7296
20 May 2010
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[自然要览]

（选自英国Nature杂志，2010年5月20日出版）


封面故事：抗疟疾新药筛选结果
Thousands of chemical starting points for antimalarial lead identification / Chemical genetics of Plasmodium falciparum
现在每年仍有近2.5亿疟疾病例见诸报道，死亡人数超过80万，其中大多数死亡者是5岁以下儿童。疟疾寄生虫镰刀形疟原虫以精于产生抗药性而著称， 所以迫切需要新药。本期Nature上的两篇研究报告让我们看到了这样的希望：通过识别数以千计能够抑制红细胞中无性阶段镰刀形疟原虫生长的化合物，也许可以找到青蒿素的替代药物，它们很多在结构和机制上都与目前的药物截然不同。Guiguemde等人发表了对超过300,000种化合物的一个化学基因组筛选结果：共有1,300 种有疗效，其中561种具有很强药效和广谱治疗作用。Gamo等人筛选了来自葛兰素史克公司化学药品数据库的近200万种药物，发现超过13,500种有疗效，其中很多对抗多种药物的分离体都有活性。这些研究提供了丰富的潜在线索，从事抗疟疾新药研究的学术机构及企业的实验室都可以免费获取。本期封面刊登的“三维等值面”所示为红细胞中镰刀形疟原虫裂殖子感染。（Articles pp. 305, 311; News & Views）


微RNA和根细胞命运（MicroRNA and root-cell fate）
Cell signalling by microRNA165/6 directs gene dose-dependent root cell fate
在经典植物模型拟南芥中对植物根发育所做的一项研究发现，一种微RNA（miRNA165/6）与细胞间的通信有关，并且是根细胞命运的一个决定因子。将水和溶质从根向茎输送的木质部微管的模式形成，被发现取决于一个新颖的双向信号作用通道，该通道涉及一个转录因子在一个方向上、microRNA在另一个方向上的细胞到细胞间的运动。这个转录因子为SHORT ROOT，是在维管柱中产生的，它进入内皮中，在那里与SCARECROW一起激发微RNA MIR165a 和166b，后者又回到维管细胞中，降解它们的目标、编码“Class III homeodomain-leucine zipper”转录因子的信使RNA。这个调控通道中由在演化上保守的转录因子和miRNA组成的一个级联的参与表明，它也许是对陆地生长条件的一种演化适应。（Article p. 316; News & Views）


超新星SN 2005E的与众不同之处（SN2005E: untrue to type）
A faint type of supernova from a white dwarf with a helium-rich companion / A massive star origin for an unusual helium-rich supernova in an elliptical galaxy
暗超新星SN 2005E的新颖性质意味着，它并不是很适合现有的超新星类别。Ib、 Ic 和 II型核心坍缩超新星被认为是当一个大质量星在其生命最后爆炸时形成的，而Ia型超新星则是一颗吸积型白矮星热核爆炸的结果。Perets等人从光谱数据得出结论认为：SN 2005E富含氦，像一颗Ib型超新星一样，缺少Ia型超新星典型的氢、硅和硫的光谱线。但基于它存在于一个“老”的恒星环境中、且喷出物较少的事实，他们认为它不是起源于一个核心坍缩超新星，而是起源于一个低质量的、老的前身星，可能是存在于一个双星体系中的一颗吸积氦的白矮星。Kawabata等人对此却有不同看法。他们说，SN 2005E像SN 2005cz，后者是一颗Ib型超新星，其不寻常之处是它是在一个椭圆形星系中被发现的。他们提出，对SN 2005E 和 SN 2005cz的最好解释是，它们是处在“大质量”低端（6-12个太阳质量）的大质量星核心坍缩的产物。在为这两篇论文配发的News & Views文章中，David Branch在关于恒星怎样爆炸的最新思想背景下对这两个模型进行了讨论。（Letters pp. 322, 326; News & Views）


柔性GaAs半导体的制备方法（Flexible GaAs semiconductors）
GaAs photovoltaics and optoelectronics using releasable multilayer epitaxial assemblies
虽然像砷化镓这样的化合物半导体在光伏电池和光电应用中与硅相比有很大的性能优势，但这些优势并不能超过生成这些材料的大型高质量层状结构、并将它们转移到柔性或透明基质上、用在如太阳能电池、夜视照相机和无线通信系统等设备中所涉及的高成本过程（所体现出的劣势）。然而现在，John Rogers及其团队演示了一个新的制造方法，它能克服这一缺点。他们是在一个单一沉降序列中、在厚的、多层组合体中来生长GaAs和AlGaAs薄膜的，然后将各层薄膜释放，通过印刷方式使其分布在异质基质上。这一策略对于大面积应用的技术潜力，通过如以玻璃为基质的场效应晶体管和以塑料为基质的光伏电池模块等GaAs装置的制造得到了演示。（Letter p. 329）


海洋的确存在变暖趋势（Warming in the oceans）
Robust warming of the global upper ocean
海洋上层起一个巨大的热汇（吸热装置）的作用，吸收了人类活动所排放的温室气体产生的绝大部分过剩能量。这使得海洋热含量潜在成为气候变化的一个关键指标。但要使其能够用于评估全球能量平衡及作为气候模型的一个限制条件，我们就需要对这样一个关键指标在测量上的不确定性有很好的了解。目前，海洋热吸收的幅度具有高度不确定性，关于年际变化模式的估计值尤其相差较大。在一项重大国际合作研究中，Lyman等人对能够获得的上层海洋热含量异常曲线进行了比较，同时分析了与它们相关的不确定性的来源，包括在校正一次性深海温度测量器的数据所存在的偏差时面临的困难。他们发现，尽管存在不确定性，但有明确而可靠的证据证明，在1993年和2008年间存在一个每平方米0.64瓦特的变暖趋势。（Letter p. 334; News & Views）


气候变暖并不会威胁到疟疾防治（Climate no danger to malaria control）
Climate change and the global malaria recession
将最近发表的一个基于证据的镰刀形疟原虫分布图与来自1900年（在主要疟疾防治措施采取之前）的数据所做一项比较表明，对温度上升会威胁到疟疾防治工作的担心是没有根据的。在全球温度上升确定无疑的一个世纪期间，疟疾的范围和强度却急剧减小。假设中的变暖所产生的效应至少要比防治措施的效应小一个数量级，这说明疟疾防治计划的成功与失败很可能是由除气候以外的其他因素决定的。（Letter p. 342）


有助于防治金黄葡萄球菌感染的新发现（Bacteria at odds）
Staphylococcus epidermidis Esp inhibits Staphylococcus aureus biofilm formation and nasal colonization
金黄葡萄球菌常见于健康人的鼻腔中，而病原体感染也经常可以追溯到这最初的良性菌落。共生菌“表皮葡萄球菌”也在鼻腔形成菌落，而且现在研究表明，由“表皮葡萄球菌”一个亚类分泌的丝氨酸蛋白酶Esp抑制金黄葡萄球菌生物膜的形成，减小金黄葡萄球菌的鼻腔菌落。这一发现为防治金黄葡萄球菌感染、包括由具有多种抗药性的菌种造成的感染提供了新方法。（Letter p. 346）


抗艾滋病病毒感染的“精英”（Resisting HIV infection）
Effects of thymic selection of the T-cell repertoire on HLA class I-associated control of HIV infection
某些艾滋病病毒感染者（被称为控制病情发展的“精英”）长期不用治疗而能保持极低的病毒负荷。在这些人中，若干种HLA Class I等位基因富集，最显著的是HLA-B57。这篇论文提供了关于这些“精英”们何以可能产生针对艾滋病病毒的有效免疫反应的一个模型。根据该模型，HLA-B57结合较少的自身肽，导致一个具有增强的交叉反应性的T细胞库，并导致针对该病毒的一个更有效的T细胞反应。这项工作对于预防接种策略也许会有意义。（Letter p. 350; News & Views）


“刚地弓线虫”的激酶目标（Kinase target in Toxoplasma gondii）
Calcium-dependent protein kinase 1 is an essential regulator of exocytosis in Toxoplasma
原生动物“刚地弓线虫”（人体中的一种机会主义病原体）分泌被称为“微丝”的细胞器，它们在寄生虫运动性、宿主-细胞入侵和退出中扮演一个关键角色。现在，这个过程被发现涉及“刚地弓线虫”依赖于钙的蛋白激酶-1(TgCDPK1)。哺乳动物宿主中这个激酶家族的缺乏使得这一蛋白成为药物设计的一个有吸引力的目标。（Letter p. 359）


芽殖酵母基因组的3D图（A genome in 3D）
A three-dimensional model of the yeast genome
芽殖酵母细胞核中染色体的三维构形已从一个分辨率为千碱基对的染色体内和染色体间相互作用图被确定，而这些相互作用则是通过高通过量染色体捕捉方法识别出的。其基因组总体形状像一个荷花（睡莲），有32个染色体臂从由细胞核一个极上簇集的“着丝点”所形成的根部伸出。这个3D图（它是一个忽略了染色体动态性质的快照）让人们首次有机会以高分辨率一睹一个真核基因组的架构，它凸显了即便是这样简单的一种生物的基因组的三维复杂性。进一步的研究工作应能揭示决定这一结构的DNA序列所遵循的普遍组织原则。（Letter p. 363）


“钙调磷酸酶”和ATF3在SCC癌症中的作用（Calcineurin versus ATF3 in cancer）
Opposing roles for calcineurin and ATF3 in squamous skin cancer
皮肤“鳞状细胞癌”(SCC)是用“钙调磷酸酶”抑制剂对器官移植患者进行免疫抑制治疗所产生的一种常见并发症。这项研究工作发现，完好的“钙调磷酸酶”- NFAT信号作用通道对于抑制SCC发展很重要，ATF3转录因子表达的增加在肿瘤发生中扮演一个关键角色。（Letter p. 368）


“肌球蛋白-II”在细胞运动中的作用（Myosin II in cell motility）
Myosin II contributes to cell-scale actin network treadmilling through network disassembly
在动物中，大多数细胞在运动时利用爬行动作来迁移，在此过程中，细胞的前端被肌动蛋白细丝的聚合所提供的力向前推进。细胞生物学家一般假设，爬行细胞的后端随后是由非肌肉“肌球蛋白-II”所产生的收缩力向前推动的。现在，对运动中的鱼角膜细胞所做观测表明，后端收缩实际上不需要收缩力。相反，“肌球蛋白-II”在通过肌动蛋白分解来帮助肌动蛋白网络运动方面有一个直接作用。（Letter p. 373）


eIF2的翻译抑制作用（Translation initiation by eIF2）
eIF5 has GDI activity necessary for translational control by eIF2 phosphorylation
帮助将抑制因子tRNA交付到核糖体的翻译因子eIF2利用GTP水解的能量来发挥功能。另一个因子eIF5已知在当eIF2与抑制因子tRNA和核糖体结合时会加快eIF2的GTP酶活性。在这项研究中，研究人员确定了eIF5的另外两个作用。一个涉及在eIF2上稳定GDP（GTP水解的产物）；另一个涉及其通过磷酸化的eIF2来发挥作用、以抑制鸟甙酸交换因子eIF2B。这些结果澄清了我们对翻译抑制怎样被调控的认识。（Letter p. 378）




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NEWS AND VIEWS
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Drug discovery: Priming the antimalarial pipeline pp297-298
Emerging resistance to existing antimalarial drugs could nullify efforts to
eliminate this deadly disease. The discovery of thousands of agents active
against malaria parasites offers hope for developing new drugs.
David A. Fidock
doi:10.1038/465297a
http://www.nature.com/nature/journal/v465/n7296/full/465297a.html

Biomaterials: Intelligent glue pp298-299
Spiders' webs are coated with microscopic droplets of glue, but the
properties of this adhesive were unclear. It has now been found that the
glue's stretchiness underpins its role in catching flies.
Haeshin Lee
doi:10.1038/465298a
http://www.nature.com/nature/journal/v465/n7296/full/465298a.html

Developmental biology: Roots respond to an inner calling pp299-300
In plant roots, patterning of two types of water-conducting xylem tissue is
determined by a signalling system that involves the reciprocal dance of a
mobile transcription factor and mobile microRNAs.
Ben Scheres
doi:10.1038/465299a
http://www.nature.com/nature/journal/v465/n7296/full/465299a.html

Extrasolar planets: Larger than they ought to be pp300-301
The finding that some gas-giant exoplanets are much larger than theory
predicts has been boggling astronomers' minds. Planetary heating caused by
gravitational tidal interactions might be a piece of the puzzle.
Pin-Gao Gu
doi:10.1038/465300a
http://www.nature.com/nature/journal/v465/n7296/full/465300a.html

DNA repair: Decision at the break point pp301-302
Many decisions affect the fate of damaged DNA [mdash] for example, how to
repair the damage, or whether to repair it at all and instead let the
damaged cell die. An intricate web of molecular interactions affects such
decisions.
Simon J. Boulton
doi:10.1038/465301a
http://www.nature.com/nature/journal/v465/n7296/full/465301a.html

Supernovae: New explosions of old stars? pp303-304
Examples of stellar explosions have emerged that fall outside the
traditional types of supernova. The nature of the stars that produce
them and the mechanism by which they explode is far from clear.
David Branch
doi:10.1038/465303a
http://www.nature.com/nature/journal/v465/n7296/full/465303a.html

Global change: The ocean is warming, isn't it? p304
A reappraisal of the messy data on upper-ocean heat content for 1993--2008
provides clear evidence for warming. But differences among various
analyses and inconsistencies with other indicators merit attention.
Kevin E. Trenberth
doi:10.1038/465304a
http://www.nature.com/nature/journal/v465/n7296/full/465304a.html

----------------------
ARTICLES
----------------------
Thousands of chemical starting points for antimalarial lead identification
pp305-310
Here, nearly 2 million compounds from GlaxoSmithKline's chemical library
were screened for inhibitors of the malaria parasite Plasmodium falciparum,
grown in red blood cells. Of these compounds, some 13,500 inhibited parasite
growth, and more than 8,000 also showed potent activity against a multidrug
resistant strain. The targets of these compounds were inferred through
bioinformatic analysis, revealing several new mechanisms of antimalarial action.
Francisco-Javier Gamo et al.
doi:10.1038/nature09107
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature09107.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature09107.html

Chemical genetics of Plasmodium falciparum pp311-315
Here, a library of more than 300,000 chemicals was screened for activity
against Plasmodium falciparum growing in red blood cells. Of these chemicals,
172 representative candidates were profiled in detail; one exemplar compound
showed efficacy in a mouse model of malaria. The findings provide the
scientific community with new starting points for drug discovery.
W. Armand Guiguemde et al.
doi:10.1038/nature09099
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature09099.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature09099.html

Cell signalling by microRNA165/6 directs gene dose-dependent root cell fate
pp316-321
A fundamental question in developmental biology is how cells communicate
positional information to pattern the tissues of an organ. Here, the
patterning of a plant's xylem tubes, which transport water and solutes
from root to shoot, is studied. A new bidirectional signalling pathway is
discovered, whereby a transcription factor moves from cell to cell in one
direction, and microRNAs move in the other direction. The result is a
differential distribution of target mRNA in the vascular cylinder,
determining xylem cell types.
Annelie Carlsbecker et al.
doi:10.1038/nature08977
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature08977.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature08977.html

----------------------
LETTERS
----------------------
A faint type of supernova from a white dwarf with a helium-rich companion
pp322-325
Supernovae are thought to arise through one of two processes. Type Ib/c and
type II supernovae are produced when the cores of massive, short-lived stars
undergo gravitational core collapse and eject a few solar masses. Type Ia
supernovae are thought to form by the thermonuclear detonation of a
carbon-oxygen white dwarf. Here a faint type Ib supernova, SN 2005E, is
reported that seems not to have had a core-collapse origin, but perhaps
arose from a low-mass, old progenitor, probably a helium-accreting white
dwarf in a binary.
H. B. Perets et al.
doi:10.1038/nature09056
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature09056.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature09056.html

A massive star origin for an unusual helium-rich supernova in an elliptical
galaxy pp326-328
The unusual supernova SN 2005E is distinguished from any supernovae
hitherto observed by several features, which are claimed to be explained
by a helium detonation in a thin surface layer of an accreting white dwarf.
The observed properties of SN 2005cz are now shown to resemble those of
SN 2005E. It is argued that these properties are best explained by a
core-collapse supernova at the low-mass end of the range of massive stars
that explode.
K. S. Kawabata et al.
doi:10.1038/nature09055
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature09055.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature09055.html

GaAs photovoltaics and optoelectronics using releasable multilayer epitaxial
assemblies pp329-333
Although compound semiconductors like gallium arsenide (GaAs) offer advantages
over silicon for photovoltaic and optoelectronic applications, these do not
outweigh the costly process of growing large layers of these materials and
transferring them to appropriate substrates. However, a new fabrication
approach is now demonstrated: films of GaAs and AlGaAs are grown in thick,
multilayered assemblies in a single sequence; the individual layers are
then released and distributed over foreign substrates by printing.
Jongseung Yoon et al.
doi:10.1038/nature09054
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature09054.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature09054.html

Robust warming of the global upper ocean pp334-337
The upper 300 m of the world's oceans act as a giant heat sink and have
absorbed the majority of the excess energy generated by anthropogenic
greenhouse gases. But the magnitude of the oceanic heat uptake is uncertain,
and differing estimates have led to questions regarding the closure of the
global energy budget. Here, a comparison of ocean heat content estimates is
presented; the conclusion is that a robust warming of 0.64 W m-2 occurred
from 1993 to 2008.
John M. Lyman et al.
doi:10.1038/nature09043
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature09043.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature09043.html

Reconciling surface plate motions with rapid three-dimensional mantle flow
around a slab edge pp338-341
The direction of tectonic plate motion at the Earth's surface and the flow
field of the mantle inferred from seismic anisotropy are well correlated
globally, implying large-scale coupling between the mantle and surface plates.
But the fit is poor at subduction zones. Here, three-dimensional numerical
models of buoyancy-driven deformation for the Alaska subduction-transform
system are used to find the origin of the regional decoupling of flow. The
results imply local rapid transport of geochemical signatures through subduction zones.
Margarete A. Jadamec and Magali I. Billen
doi:10.1038/nature09053
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature09053.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature09053.html

Climate change and the global malaria recession pp342-345
Rising global temperatures resulting from climate change have been predicted to
increase the future incidence of infectious diseases, including malaria. However,
it is known that the range of malaria has contracted through a century of economic
development and disease control. This contraction has now been quantified, and
compared with the predicted effects of climate on malaria incidence. It is
suggested that the impact of rising temperature is likely to be minor.
Peter W. Gething et al.
doi:10.1038/nature09098
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature09098.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature09098.html

Staphylococcus epidermidis Esp inhibits Staphylococcus aureus biofilm formation
and nasal colonization pp346-349
Staphylococcus epidermis is a commensal bacterium found in the human nasal
cavity. It is now shown that a subset of S. epidermis secretes the serine
protease Esp, and that this directly reduces the colonization of the nasal
cavity by the pathogen S. aureus. The findings reveal a new mechanism of
bacterial interference, which could lead to the development of new drugs to
prevent S. aureus colonization and infection.
Tadayuki Iwase et al.
doi:10.1038/nature09074
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature09074.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature09074.html

Effects of thymic selection of the T-cell repertoire on HLA class[thinsp]I-associated
control of HIV infection pp350-354
'Elite controllers' are rare people who are infected with HIV but maintain low
levels of HIV RNA without being treated, making it unlikely that they will develop
AIDS. Certain HLA class I alleles, notably HLA-B57, are enriched in elite controllers.
Here a model is proposed to explain how such elite controllers generate an effective
immune response against HIV. In this model, HLA-B57 binds to fewer self-peptides,
resulting in a T-cell repertoire with enhanced cross-reactivity and leading to a
more effective T-cell response to the virus.
Andrej Kosmrlj et al.
doi:10.1038/nature08997
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature08997.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature08997.html

Modulation of Shigella virulence in response to available oxygen in vivo
pp355-358
The bacterium Shigella flexneri, which causes dysentery, infects the gastrointestinal
tract. It uses a type III secretion system as a molecular syringe to inject
virulence factors into host cells during infection. It is now suggested that
varying oxygen availability during different phases of infection tightly regulates
expression of the secretion system, as well as the secretion of virulence factors.
Benoit Marteyn et al.
doi:10.1038/nature08970
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature08970.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature08970.html

Calcium-dependent protein kinase 1 is an essential regulator of exocytosis in
Toxoplasma pp359-362
Toxoplasma gondii is an opportunistic human pathogen that secretes organelles
called micronemes during infection. This is important for parasite motility,
host-cell invasion and egress. It is now shown that the secretion of micronemes
is dependent on the T. gondii calcium-dependent protein kinase 1. This kinase is
not found in the parasite's mammalian hosts, and might represent a valid drug target.
Sebastian Lourido et al.
doi:10.1038/nature09022
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature09022.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature09022.html

A three-dimensional model of the yeast genome pp363-367
The topologies of, and spatial relationships between, chromosomes are important
but poorly understood. Here, a high-throughput method is used to study intra- and
inter-chromosomal interactions in Saccharomyces cerevisiae. A map of the haploid
genome is generated at kilobase resolution, and is used to construct a
three-dimensional model of the yeast genome. The findings provide a glimpse of
the interface between the form and function of a eukaryotic genome.
Zhijun Duan et al.
doi:10.1038/nature08973
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature08973.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature08973.html

Opposing roles for calcineurin and ATF3 in squamous skin cancer pp368-372
Calcineurin inhibitors are the mainstay of immunosuppressive treatment for organ
transplant recipients. However, treatment with these drugs commonly leads to
squamous cell carcinoma (SCC) of the skin. It is shown here that an intact
calcineurin/NFAT signalling pathway is important for suppressing SCC development.
Inhibition of this pathway leads to increased expression of the ATF3 protein,
which has a key role in tumorigenesis.
Xunwei Wu et al.
doi:10.1038/nature08996
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature08996.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature08996.html

Myosin II contributes to cell-scale actin network treadmilling through network
disassembly pp373-377
Eukaryotic cells crawl through a process in which the front of the cell is
propelled forwards by the force provided by polymerization of actin filaments.
These must be disassembled at the rear of the cell to allow sustained motility.
It is now shown that non-muscle myosin II protein is needed for the disassembly
of actin networks at the rear of crawling cells.
Cyrus A. Wilson et al.
doi:10.1038/nature08994
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature08994.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature08994.html

eIF5 has GDI activity necessary for translational control by eIF2 phosphorylation
pp378-381
The initiation of protein synthesis requires the eukaryotic translation initiation
factor (eIF) 2, which uses energy from the hydrolysis of GTP. Another factor,
eIF5, accelerates the GTP-hydrolysing activity of eIF2. Here, two other roles
for eIF5 have been defined. One involves stabilizing GDP, the product of GTP
hydrolysis, on eIF2. In its other role, eIF5 works with phosphorylated eIF2 to
inhibit the guanine-nucleotide exchange factor eIF2B. These results clarify our
understanding of how the initiation of translation is regulated.
Martin D. Jennings and Graham D. Pavitt
doi:10.1038/nature09003
Abstract: http://www.nature.com/nature/journal/v465/n7296/abs/nature09003.html
Article: http://www.nature.com/nature/journal/v465/n7296/full/nature09003.html