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131.
Autoregulated instability of beta-tubulin mRNAs by recognition of the nascent amino terminus of beta-tubulin 总被引:54,自引:0,他引:54
Tubulin synthesis in animal cells is controlled by an autoregulatory mechanism that modulates the stability of polysome-bound tubulin messenger RNAs. The beta-tubulin RNAs are selectively targeted as substrates for destabilization not through the recognition of specific RNA sequences, but rather through co-translational recognition of the amino-terminal beta-tubulin tetrapeptide after its emergence from the ribosome. This motif is likely to be used in other systems where RNA degradation is coupled to ribosome attachment and translation. 相似文献
132.
Zusammenfassung Die endst?ndige N-Methyl-Gruppe von 1-Methyl-C14-2-p-(isopropylcarbamoyl)benzylhydrazin-Hydrochlorid (MBH) (Ro 4-6467) erwies sich in In-vivo-Experimenten metabolisch labil,
wird teilweise oxydiert und Bestandteil des Formiatpools.
相似文献
133.
In the unactivated Limulus sperm, a 60- micro m-long bundle of actin filaments crosslinked by the protein scruin is bent and twisted into a coil around the base of the nucleus. At fertilization, the bundle uncoils and fully extends in five seconds to support a finger of membrane known as the acrosomal process. This biological spring is powered by stored elastic energy and does not require the action of motor proteins or actin polymerization. In a 9.5-A electron cryomicroscopic structure of the extended bundle, we show that twist, tilt and rotation of actin-scruin subunits deviate widely from a 'standard' F-actin filament. This variability in structural organization allows filaments to pack into a highly ordered and rigid bundle in the extended state and suggests a mechanism for storing and releasing energy between coiled and extended states without disassembly. 相似文献
134.
Als TD Vila R Kandul NP Nash DR Yen SH Hsu YF Mignault AA Boomsma JJ Pierce NE 《Nature》2004,432(7015):386-390
Large blue (Maculinea) butterflies are highly endangered throughout the Palaearctic region, and have been the focus of intense conservation research. In addition, their extraordinary parasitic lifestyles make them ideal for studies of life history evolution. Early instars consume flower buds of specific host plants, but later instars live in ant nests where they either devour the brood (predators), or are fed mouth-to-mouth by the adult ants (cuckoos). Here we present the phylogeny for the group, which shows that it is a monophyletic clade nested within Phengaris, a rare Oriental genus whose species have similar life histories. Cuckoo species are likely to have evolved from predatory ancestors. As early as five million years ago, two Maculinea clades diverged, leading to the different parasitic strategies seen in the genus today. Contrary to current belief, the two recognized cuckoo species show little genetic divergence and are probably a single ecologically differentiated species. On the other hand, some of the predatory morphospecies exhibit considerable genetic divergence and may contain cryptic species. These findings have important implications for conservation and reintroduction efforts. 相似文献
135.
Cheung NS Choy MS Halliwell B Teo TS Bay BH Lee AY Qi RZ Koh VH Whiteman M Koay ES Chiu LL Zhu HJ Wong KP Beart PM Cheng HC 《Cellular and molecular life sciences : CMLS》2004,61(15):1926-1934
The tumor suppressor function of PTEN is attributed to its phospholipid phosphatase activity that
dephosphorylates the plasma membrane phosphatidylinositol-(3,4,5)-triphosphate
[PtdIns(3,4,5)P3]. Implicit in this notion is that PTEN needs to be targeted to the plasma
membrane to dephosphorylate PtdIns(3,4,5)P3. However, the recruitment of PTEN to the plasma
membrane is not fully understood. Here, we demonstrate PTEN accumulation in the detergent-insoluble fraction of
neuronal cells in response to treatment by the proteasome inhibitor lactacystin. First, lactacystin induces
apoptosis and the activation of caspase-3 in cultured cortical neurons. Second, PTEN undergoes proteolysis to
form a truncated 50-kDa form that lacks parts of its C-terminal tail. Third, the truncated PTEN is stably
associated with the detergent-insoluble fraction in which the plasma membrane marker protein flotillin-1 resides.
Taken together, our results suggest that truncation and accumulation of PTEN to the detergent-insoluble membrane
fraction are two events associated with the apoptotic signals of the proteasome inhibitor in cortical neurons.Received 24 March 2004; received after revision 26 May 2004; accepted 5 June 2004 相似文献
136.
从红花锦鸡儿的根中提取分离得三个化学成份,经IR、MS、HNMR等波谱数据及文献资料鉴定为β-谷甾醇,C_(28)脂肪酸,芦丁. 相似文献
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