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91.
Eukaryotic cells have developed a diverse repertoire of Rab GTPases to regulate vesicle trafficking pathways. Together with their effector proteins, Rabs mediate various aspects of vesicle formation, tethering, docking and fusion, but details of the biological roles elicited by effectors are largely unknown. Human Rab6 is involved in the trafficking of vesicles at the level of Golgi via interactions with numerous effector proteins. We have previously determined the crystal structure of Rab6 in complex with DENND5, alternatively called Rab6IP1, which comprises two RUN domains (RUN1 and RUN2) separated by a PLAT domain. The structure of Rab6/RUN1-PLAT (Rab6/R1P) revealed the molecular basis for Golgi recruitment of DENND5 via the RUN1 domain, but the functional role of the RUN2 domain has not been well characterized. Here we show that a soluble DENND5 construct encompassing the RUN2 domain binds to the N-terminal region of sorting nexin 1 by surface plasmon resonance analyses. 相似文献
92.
ag13 is expressed in Alnus glutinosa nodules in infected cells during endosymbiont degradation and in the nodule pericycle 总被引:1,自引:0,他引:1
Changhui Guan Antoon D. L. Akkermans Ab van Kammen Ton Bisseling Katharina Pawlowski 《Physiologia plantarum》1997,99(4):601-607
We isolated and characterized an Alnus glutinosa cDNA clone, pAg13, which corresponds to a gene expressed at higher levels in nodules induced by Frankia than in roots. The deduced polypeptide sequence is rich in glutamic acid and proline and contains a putative signal peptide indicating an extracellular location of Ag13. In situ hybridization showed that ag13 is expressed in the pericycle of the nodule vascular bundle and in infected cells that exhibited degradation of the endosymbiont. 相似文献
93.
McCormick MM Rahimi F Bobryshev YV Gaus K Zreiqat H Cai H Lord RS Geczy CL 《The Journal of biological chemistry》2005,280(50):41521-41529
Atherogenesis is a complex process involving inflammation. S100A8 and S100A9, the Ca2+-binding neutrophil cytosolic proteins, are associated with innate immunity and regulate processes leading to leukocyte adhesion and transmigration. In neutrophils and monocytes the S100A8-S100A9 complex regulates phosphorylation, NADPH-oxidase activity, and fatty acid transport. The proteins have anti-microbial properties, and S100A8 may play a role in oxidant defense in inflammation. Murine S100A8 is regulated by inflammatory mediators and recruits macrophages with a proatherogenic phenotype. S100A9 but not S100A8 was found in macrophages in ApoE-/- murine atherosclerotic lesions, whereas both proteins are expressed in human giant cell arteritis. Here we demonstrate S100A8 and S100A9 protein and mRNA in macrophages, foam cells, and neovessels in human atheroma. Monomeric and complexed forms were detected in plaque extracts. S100A9 was strongly expressed in calcifying areas and the surrounding extracellular matrix. Vascular matrix vesicles contain high levels of Ca2+-binding proteins and phospholipids that regulate calcification. Matrix vesicles characterized by electron microscopy, x-ray microanalysis, nucleoside triphosphate pyrophosphohydrolase assay and cholesterol/phospholipid analysis contained predominantly S100A9. We propose that S100A9 associated with lipid structures in matrix vesicles may influence phospholipid-Ca2+ binding properties to promote dystrophic calcification. S100A8 and S100A9 were more sensitive to hypochlorite oxidation than albumin or low density lipoprotein and immunoaffinity confirmed S100A8-S100A9 complexes; some were resistant to reduction, suggesting that hypochlorite may contribute to protein cross-linking. S100A8 and S100A9 in atherosclerotic plaque and calcifying matrix vesicles may significantly influence redox- and Ca2+-dependent processes during atherogenesis and its chronic complications, particularly dystrophic calcification. 相似文献
94.
Michael W. Lloyd Robert K. BurnettJr. Katharina A. M. Engelhardt Maile C. Neel 《Conservation Genetics》2012,13(3):753-765
The goal of ecological restoration is to re-establish self-sustaining ecosystems that will resist future perturbation without
additional human input. We focus here on the re-establishment of submersed aquatic macrophyte beds in the restoration of the
Chesapeake Bay estuary. Degraded environmental conditions are often to blame for poor bed establishment, but genetic factors
could also be contributing to low survival. We quantified the effect of restoration practices on genetic diversity in the
submersed aquatic plant species Vallisneria americana Michx. (Hydrocharitaceae) in the Chesapeake Bay. In 2007, we collected 440 shoots from 8 restored/natural site pairs and
4 restoration stock repositories, and genotyped those individuals at 10 microsatellite loci. Restoration practices do not
appear to negatively impact genetic diversity, and basic measures of genetic diversity within restored sites overlap with
natural sites. However, small population size of restored sites, significant inbreeding coefficients within 3 sites, and low
overlap of allele composition among sites provide cause for concern. These problems are relatively minor, and we propose several
corrections that would alleviate them altogether. Managers should be encouraged by our findings as well as the current state
of the genetic diversity within V. americana restoration efforts. 相似文献
95.
96.
Stephanie J. Gros Nina Kurschat Astrid Drenckhan Thorsten Dohrmann Evelyn Forberich Katharina Effenberger Uta Reichelt Robert M. Hoffman Klaus Pantel Jussuf T. Kaifi Jakob R. Izbicki 《PloS one》2012,7(10)
A functional linkage of the structurally unrelated receptors HER2 and CXCR4 has been suggested for breast cancer but has not been evaluated for esophageal carcinoma. The inhibition of HER2 leads to a reduction of primary tumor growth and metastases in an orthotopic model of esophageal carcinoma. The chemokine receptor CXCR4 has been implicated in metastatic dissemination of various tumors and correlates with poor survival in esophageal carcinoma. The aim of this study was to investigate a correlation between the expression levels of HER2 and CXCR4 and to evaluate the involvemnent of CXCR4-expression in HER2-positive esophageal carcinoma. The effects of HER2-inhibition with trastuzumab and of CXCR4-inhibition with AMD3100 on primary tumor growth, metastatic homing, and receptor expression were evaluated in vitro and in an orthotopic model of metastatic esophageal carcinoma using MRI for imaging. The clinical relevance of HER2- and CXCR4-expression was examined in esophageal carcinoma patients. A significant correlation of HER2- and CXCR4-expression in primary tumor and metastases exists in the orthotopic model. Trastuzumab and AMD3100 treatment led to a significant reduction of primary tumor growth, metastases and micrometastases. HER2-expression was significantly elevated under AMD3100 treatment in the primary tumor and particularly in the metastases. The positive correlation between HER2- and CXCR4-expression was validated in esophageal cancer patients. The correlation of CXCR4- and HER2-expression and the elevation of HER2-expression and reduction of metastases through CXCR4-inhibition suggest a possible functional linkage and a role in tumor dissemination in HER2-positive esophageal carcinoma. 相似文献
97.
Stephan Wilmes Oliver Beutel Zhi Li Véronique Francois-Newton Christian P. Richter Dennis Janning Cindy Kroll Patrizia Hanhart Katharina H?tte Changjiang You Gilles Uzé Sandra Pellegrini Jacob Piehler 《The Journal of cell biology》2015,209(4):579-593
Type I interferons (IFNs) activate differential cellular responses through a shared cell surface receptor composed of the two subunits, IFNAR1 and IFNAR2. We propose here a mechanistic model for how IFN receptor plasticity is regulated on the level of receptor dimerization. Quantitative single-molecule imaging of receptor assembly in the plasma membrane of living cells clearly identified IFN-induced dimerization of IFNAR1 and IFNAR2. The negative feedback regulator ubiquitin-specific protease 18 (USP18) potently interferes with the recruitment of IFNAR1 into the ternary complex, probably by impeding complex stabilization related to the associated Janus kinases. Thus, the responsiveness to IFNα2 is potently down-regulated after the first wave of gene induction, while IFNβ, due to its ∼100-fold higher binding affinity, is still able to efficiently recruit IFNAR1. Consistent with functional data, this novel regulatory mechanism at the level of receptor assembly explains how signaling by IFNβ is maintained over longer times compared with IFNα2 as a temporally encoded cause of functional receptor plasticity. 相似文献
98.
Summary The localization of two carbohydrate binding proteins, so-called lectins, was studied in the sponge tissue of Axinella polypoides by light and immunofluorescence microscopy. They do not occur at the cellular surface of any cell type, but they are stored in vesicles of the spherulous cells. After short formaldehyde fixation spherulous cells can be isolated and they release the active lectins upon lysis in distilled water.Electron microscopical studies of spherulous cells show that they contain almost nothing else but a small nucleus and vesicles of different size and number. Small vesicles are full of an electron dense material, whereas the content of large vesicles has a fluffy and fibrillar structure. Spherulous cells are large and tightly packed in the outer layer of the ectosome and in the mesh work of the spongin fibres of the central axis. They are small and scattered in the inner layer of the ectosome, and they are found throughout the choanosome. The function of the lectins is not clearly defined, and different alternatives such as participation in glycoprotein synthesis, immunological defense, or carbohydrate transport are possible.This study was supported by a grant from the Deutsche ForschungsgemeinschaftWe are gratefully indebted to Dr. D. Keyser for his help in our electron microscopical studies 相似文献
99.
Katharina Dalton 《BMJ (Clinical research ed.)》1982,284(6325):1332-1333
100.
Katharina T. Huber Vincent Moulton Charles Semple Taoyang Wu 《Bulletin of mathematical biology》2018,80(8):2137-2153
An important problem in phylogenetics is the construction of phylogenetic trees. One way to approach this problem, known as the supertree method, involves inferring a phylogenetic tree with leaves consisting of a set X of species from a collection of trees, each having leaf-set some subset of X. In the 1980s, Colonius and Schulze gave certain inference rules for deciding when a collection of 4-leaved trees, one for each 4-element subset of X, can be simultaneously displayed by a single supertree with leaf-set X. Recently, it has become of interest to extend this and related results to phylogenetic networks. These are a generalization of phylogenetic trees which can be used to represent reticulate evolution (where species can come together to form a new species). It has recently been shown that a certain type of phylogenetic network, called a (unrooted) level-1 network, can essentially be constructed from 4-leaved trees. However, the problem of providing appropriate inference rules for such networks remains unresolved. Here, we show that by considering 4-leaved networks, called quarnets, as opposed to 4-leaved trees, it is possible to provide such rules. In particular, we show that these rules can be used to characterize when a collection of quarnets, one for each 4-element subset of X, can all be simultaneously displayed by a level-1 network with leaf-set X. The rules are an intriguing mixture of tree inference rules, and an inference rule for building up a cyclic ordering of X from orderings on subsets of X of size 4. This opens up several new directions of research for inferring phylogenetic networks from smaller ones, which could yield new algorithms for solving the supernetwork problem in phylogenetics. 相似文献