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Specificity Factor (specificity + factor)
Selected AbstractsXenopus Rbm9 is a novel interactor of XGld2 in the cytoplasmic polyadenylation complexFEBS JOURNAL, Issue 3 2008Catherine Papin During early development, control of the poly(A) tail length by cytoplasmic polyadenylation is critical for the regulation of specific mRNA expression. Gld2, an atypical poly(A) polymerase, is involved in cytoplasmic polyadenylation in Xenopus oocytes. In this study, a new XGld2-interacting protein was identified: Xenopus RNA-binding motif protein 9 (XRbm9). This RNA-binding protein is exclusively expressed in the cytoplasm of Xenopus oocytes and interacts directly with XGld2. It is shown that XRbm9 belongs to the cytoplasmic polyadenylation complex, together with cytoplasmic polyadenylation element-binding protein (CPEB), cleavage and polyadenylation specificity factor (CPSF) and XGld2. In addition, tethered XRbm9 stimulates the translation of a reporter mRNA. The function of XGld2 in stage VI oocytes was also analysed. The injection of XGld2 antibody into oocytes inhibited polyadenylation, showing that endogenous XGld2 is required for cytoplasmic polyadenylation. Unexpectedly, XGld2 and CPEB antibody injections also led to an acceleration of meiotic maturation, suggesting that XGld2 is part of a masking complex with CPEB and is associated with repressed mRNAs in oocytes. [source] The t(1;9)(p34;q34) and t(8;12)(p11;q15) fuse pre-mRNA processing proteins SFPQ (PSF) and CPSF6 to ABL and FGFR1GENES, CHROMOSOMES AND CANCER, Issue 5 2008Claire Hidalgo-Curtis We have investigated two patients with acquired chromosomal rearrangements, a male presenting with a t(1;9)(p34;q34) and B cell progenitor acute lymphoid leukemia and a female presenting with a t(8;12)(p11;q15) and the 8p11 myeloproliferative syndrome. We determined that the t(1;9) fused ABL to SFPQ (also known as PSF), a gene mapping to 1p34 that encodes a polypyrimidine tract-binding protein-associated splicing factor. The t(8;12) fused CPSF6, a cleavage and polyadenylation specificity factor, to FGFR1. The fusions were confirmed by amplification of the genomic breakpoints and RT-PCR. The predicted oncogenic products of these fusions, SFPQ-ABL and CPSF6-FGFR1, are in-frame and encode the N-terminal domain of the partner protein and the entire tyrosine kinase domain and C-terminal sequences of ABL and FGFR1. SFPQ interacts with two FGFR1 fusion partners, ZNF198 and CPSF6, that are functionally related to the recurrent PDGFR, partner FIP1L1. Our findings thus identify a group of proteins that are important for pre-mRNA processing as fusion partners for tyrosine kinases in hematological malignancies. © 2008 Wiley-Liss, Inc. [source] Contributions of diffusional limitation, photoinhibition and photorespiration to midday depression of photosynthesis in Arisaema heterophyllum in natural high lightPLANT CELL & ENVIRONMENT, Issue 3 2000Hiroyuki Muraoka ABSTRACT Diurnal changes in photosynthetic gas exchange and chlorophyll fluorescence were measured under full sunlight to reveal diffusional and non-diffusional limitations to diurnal assimilation in leaves of Arisaema heterophyllum Blume plants grown either in a riparian forest understorey (shade leaves) or in an adjacent deforested open site (sun leaves). Midday depressions of assimilation rate (A) and leaf conductance of water vapour were remarkably deeper in shade leaves than in sun leaves. To evaluate the diffusional (i.e. stomatal and leaf internal) limitation to assimilation, we used an index [1,A/A350], in which A350 is A at a chloroplast CO2 concentration of 350 ,mol mol,1. A350 was estimated from the electron transport rate (JT), determined fluorometrically, and the specificity factor of Rubisco (S), determined by gas exchange techniques. In sun leaves under saturating light, the index obtained after the ,peak' of diurnal assimilation was 70% greater than that obtained before the ,peak', but in shade leaves, it was only 20% greater. The photochemical efficiency of photosystem II (,F/Fm,) and thus JT was considerably lower in shade leaves than in sun leaves, especially after the ,peak'. In shade leaves but not in sun leaves, A at a photosynthetically active photon flux density (PPFD) > 500 ,mol m,2 s,1 depended positively on JT throughout the day. Electron flows used by the carboxylation and oxygenation (JO) of RuBP were estimated from A and JT. In sun leaves, the JO/JT ratio was significantly higher after the ,peak', but little difference was found in shade leaves. Photorespiratory CO2 efflux in the absence of atmospheric CO2 was about three times higher in sun leaves than in shade leaves. We attribute the midday depression of assimilation in sun leaves to the increased rate of photorespiration caused by stomatal closure, and that in shade leaves to severe photoinhibition. Thus, for sun leaves, increased capacities for photorespiration and non-photochemical quenching are essential to avoid photoinhibitory damage and to tolerate high leaf temperatures and water stress under excess light. The increased Rubisco content in sun leaves, which has been recognized as raising photosynthetic assimilation capacity, also contributes to increase in the capacity for photorespiration. [source] Crystallization and preliminary X-ray crystallographic analysis of MinE, the cell-division topological specificity factor from Helicobacter pyloriACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 5 2010Gil Bu Kang Cell division in Gram-negative bacteria is driven by the formation of an FtsZ ring at the division site. MinE regulates the proper placement of the FtsZ ring at mid-cell by blocking the inhibitory action of the MinCD complex. Diffraction data were collected at 2.8,Å resolution from a native crystal of full-length Helicobacter pylori MinE. The crystal belonged to space group P64. Assuming the presence of two molecules in the asymmetric unit, the calculated Matthews coefficient was 2.58,Å3,Da,1, which corresponds to a solvent content of 52.3%. For MAD phasing, a four-wavelength data set was collected at 3.0,Å resolution. [source] | ||||||||||