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21.
tRNase Z: the end is not in sight 总被引:1,自引:0,他引:1
Although the enzyme tRNase Z has only recently been isolated, a plethora of data has already been acquired concerning the
enzyme. tRNase Z is the endonuclease that catalyzes the removal of the tRNA 3′ trailer, yielding the mature tRNA 3′ end ready
for CCA addition and aminoacylation. Another substrate cleaved by tRNase Z is the small chromogenic phosphodiester bis(p-nitrophenyl)phosphate (bpNPP), which is the smallest tRNase Z substrate known so far. Hitherto the biological function as
tRNA 3′-end processing enzyme has been shown only in one prokaryotic and one eukaryotic organism, respectively. This review
summarizes the present information concerning the two tRNase Z substrates pre-tRNA and bpNPP, as well as the metal requirements
of tRNase Z enzymes.
Received 29 March 2007; received after revision 15 May 2007; accepted 21 May 2007 相似文献
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Ebstein F Kloetzel PM Krüger E Seifert U 《Cellular and molecular life sciences : CMLS》2012,69(15):2543-2558
The proteasome is a multi-catalytic protein complex whose primary function is the degradation of abnormal or foreign proteins. Upon exposure of cells to interferons (IFNs), the β1i/LMP2, β2i/MECL-1, and β5i/LMP7 subunits are induced and incorporated into newly synthesized immunoproteasomes (IP), which are thought to function solely as critical players in the optimization of the CD8(+) T-cell response. However, the observation that IP are present in several non-immune tissues under normal conditions and/or following pathological events militates against the view that its role is limited to MHC class I presentation. In support of this concept, the recent use of genetic models deficient for β1i/LMP2, β2i/MECL-1, or β5i/LMP7 has uncovered unanticipated functions for IP in innate immunity and non-immune processes. Herein, we review recent data in an attempt to clarify the role of IP beyond MHC class I epitope presentation with emphasis on its involvement in the regulation of protein homeostasis, cell proliferation, and cytokine gene expression. 相似文献
24.
Maize HapMap2 identifies extant variation from a genome in flux 总被引:3,自引:0,他引:3
Chia JM Song C Bradbury PJ Costich D de Leon N Doebley J Elshire RJ Gaut B Geller L Glaubitz JC Gore M Guill KE Holland J Hufford MB Lai J Li M Liu X Lu Y McCombie R Nelson R Poland J Prasanna BM Pyhäjärvi T Rong T Sekhon RS Sun Q Tenaillon MI Tian F Wang J Xu X Zhang Z Kaeppler SM Ross-Ibarra J McMullen MD Buckler ES Zhang G Xu Y Ware D 《Nature genetics》2012,44(7):803-807
Whereas breeders have exploited diversity in maize for yield improvements, there has been limited progress in using beneficial alleles in undomesticated varieties. Characterizing standing variation in this complex genome has been challenging, with only a small fraction of it described to date. Using a population genetics scoring model, we identified 55 million SNPs in 103 lines across pre-domestication and domesticated Zea mays varieties, including a representative from the sister genus Tripsacum. We find that structural variations are pervasive in the Z. mays genome and are enriched at loci associated with important traits. By investigating the drivers of genome size variation, we find that the larger Tripsacum genome can be explained by transposable element abundance rather than an allopolyploid origin. In contrast, intraspecies genome size variation seems to be controlled by chromosomal knob content. There is tremendous overlap in key gene content in maize and Tripsacum, suggesting that adaptations from Tripsacum (for example, perennialism and frost and drought tolerance) can likely be integrated into maize. 相似文献
25.
Panizzi JR Becker-Heck A Castleman VH Al-Mutairi DA Liu Y Loges NT Pathak N Austin-Tse C Sheridan E Schmidts M Olbrich H Werner C Häffner K Hellman N Chodhari R Gupta A Kramer-Zucker A Olale F Burdine RD Schier AF O'Callaghan C Chung EM Reinhardt R Mitchison HM King SM Omran H Drummond IA 《Nature genetics》2012,44(6):714-719
Cilia are essential for fertilization, respiratory clearance, cerebrospinal fluid circulation and establishing laterality. Cilia motility defects cause primary ciliary dyskinesia (PCD, MIM244400), a disorder affecting 1:15,000-30,000 births. Cilia motility requires the assembly of multisubunit dynein arms that drive ciliary bending. Despite progress in understanding the genetic basis of PCD, mutations remain to be identified for several PCD-linked loci. Here we show that the zebrafish cilia paralysis mutant schmalhans (smh(tn222)) encodes the coiled-coil domain containing 103 protein (Ccdc103), a foxj1a-regulated gene product. Screening 146 unrelated PCD families identified individuals in six families with reduced outer dynein arms who carried mutations in CCDC103. Dynein arm assembly in smh mutant zebrafish was rescued by wild-type but not mutant human CCDC103. Chlamydomonas Ccdc103/Pr46b functions as a tightly bound, axoneme-associated protein. These results identify Ccdc103 as a dynein arm attachment factor that causes primary ciliary dyskinesia when mutated. 相似文献
26.
Dobbins SE Broderick P Melin B Feychting M Johansen C Andersson U Brännström T Schramm J Olver B Lloyd A Ma YP Hosking FJ Lönn S Ahlbom A Henriksson R Schoemaker MJ Hepworth SJ Hoffmann P Mühleisen TW Nöthen MM Moebus S Eisele L Kosteljanetz M Muir K Swerdlow A Simon M Houlston RS 《Nature genetics》2011,43(9):825-827
To identify susceptibility loci for meningioma, we conducted a genome-wide association study of 859 affected individuals (cases) and 704 controls with validation in two independent sample sets totaling 774 cases and 1,764 controls. We identified a new susceptibility locus for meningioma at 10p12.31 (MLLT10, rs11012732, odds ratio = 1.46, P(combined) = 1.88 × 10(-14)). This finding advances our understanding of the genetic basis of meningioma development. 相似文献
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28.
Apolipoprotein M (apoM) is a novel apolipoprotein found mainly in high-density lipoproteins (HDL). Its function is yet to
be defined. ApoM (25 kDa) has a typical lipocalin ?-barrel fold and a hydrophobic pocket. Retinoids bind apoM but with low
affinity and may not be the natural ligands. ApoM retains its signal peptide, which serves as a hydrophobic anchor to the
lipoproteins. This prevents apoM from being lost in the urine. Approximately 5% of HDL carries an apoM molecule. ApoM in plasma
(1 μM) correlates strongly with both low-density lipoprotein (LDL) and HDL cholesterol, suggesting a link to cholesterol metabolism.
However, in casecontrol studies, apoM levels in patients with coronary heart disease (CHD) and controls were similar, suggesting
apoM levels not to affect the risk for CHD in humans. Experiments in transgenic mice suggested apoM to have antiatherogenic
properties; possible mechanisms include increased formation of pre-? HDL, enhanced cholesterol mobilization from foam cells,
and increased antioxidant properties.
Received 28 November 2008; received after revision 15 December 2008; accepted 16 December 2008 相似文献
29.
Kärt Varendi Anmol Kumar Mari-Anne Härma Jaan-Olle Andressoo 《Cellular and molecular life sciences : CMLS》2014,71(22):4443-4456
Brain-derived neurotrophic factor (BDNF) is a secreted protein of the neurotrophin family that regulates brain development, synaptogenesis, memory and learning, as well as development of peripheral organs, such as angiogenesis in the heart and postnatal growth and repair of skeletal muscle. However, while precise regulation of BDNF levels is an important determinant in defining the biological outcome, the role of microRNAs (miRs) in modulating BDNF expression has not been extensively analyzed. Using in silico approaches, reporter systems, and analysis of endogenous BDNF, we show that miR-1, miR-10b, miR-155, and miR-191 directly repress BDNF through binding to their predicted sites in BDNF 3′UTR. We find that the overexpression of miR-1 and miR-10b suppresses endogenous BDNF protein levels and that silencing endogenous miR-10b increases BDNF mRNA and protein levels. Furthermore, we show that miR-1/206 binding sites within BDNF 3′UTR are used in differentiated myotubes but not in undifferentiated myoblasts. Finally, our data from two cell lines suggest that endogenous miR-1/206 and miR-10 family miRs act cooperatively in suppressing BDNF through their predicted sites in BDNF 3′UTR. In conclusion, our results highlight miR-1, miR-10b, miR-155, and miR-191 as novel regulators of BDNF long and short 3′UTR isoforms, supporting future research in different physiological and pathological contexts. 相似文献
30.