Determination of Vacant Lattice Sites in Aluminium Alloys by X-ray Diffraction Technique

THE study of the structure of metals and alloys is very important because this affords the possibility of developing new alloys with improved properties to be useful for meeting service requirements. Theories based on ideal crystals fail miserably when applied to real crystals of the metals and alloys, for example the calculated Yield strength and breaking strength of ideal crystals are 100 to 10,000 times more than the observed strength of real crystals. The reason is that the crystals contain many haws and irregularities, so it is felt that a detailed knowledge of vacant lattice sites in alloys will be useful, because of their effects on physical and mechanical properties. The object of this investigation is to find out the effect of copper on the lattice parameter and vacant lattice sites in aluminium

The Wntome: A genome-wide analysis of kinases and phosphatases that regulate Wnt signaling

Evolutionarily conserved cell signaling pathways regulate diverse and indispensable processes during metazoan development. A precise control of both the state and threshold of signaling is required for normal development to occur. Cells predominantly utilize the kinase- and phosphatase-mediated reversible phosphorylation of proteins to control signaling. The canonical Wnt signaling pathway has homologous roles during the processes of axis polarization and stem cell maintenance in diverse metazoans. Wnt signaling is regulated through reversible phosphorylation both in its silent and active state. We have identified and characterized the function of Drosophila Hipk, a novel kinase component of the pathway. Genetic and biochemical analyses suggest that Hipk stabilizes the pathway effector Armadillo in a process that is dependent on its catalytic activity. Additionally, Hipk acts to promote pathway activity independent of its effect on Armadillo stability. We find that Hipk2 has a functionally conserved role to regulate Wnt signaling in mammalian cells. Hipk and a limited number of other kinases (and phosphatases) have thus far been implicated in the regulation of Wnt signaling. We have performed an in vivo loss-of-function RNAi screen to identify additional enzymes that regulate this pathway through reversible phosphorylation in Drosophila. Our analyses have identified novel pathway components at all levels of the Wnt signaling relay

Endosome-ER Contacts Control Actin Nucleation and Retromer Function through VAP-Dependent Regulation of PI4P

VAP (VAPA and VAPB) is an evolutionarily conserved endoplasmic reticulum (ER)-anchored protein that helps generate tethers between the ER and other membranes through which lipids are exchanged across adjacent bilayers. Here, we report that by regulating PI4P levels on endosomes, VAP affects WASH-dependent actin nucleation on these organelles and the function of the retromer, a protein coat responsible for endosome-to-Golgi traffic. VAP is recruited to retromer budding sites on endosomes via an interaction with the retromer SNX2 subunit. Cells lacking VAP accumulate high levels of PI4P, actin comets, and trans-Golgi proteins on endosomes. Such defects are mimicked by downregulation of OSBP, a VAP interactor and PI4P transporter that participates in VAP-dependent ER-endosomes tethers. These results reveal a role of PI4P in retromer-/WASH-dependent budding from endosomes. Collectively, our data show how the ER can control budding dynamics and association with the cytoskeleton of another membrane by direct contacts leading to bilayer lipid modifications.Accepted versio

Spatial snapshots of amyloid precursor protein intramembrane processing via early endosome proteomics

Methods to assess organellar content are important. Here, Park et al develop a method for rapid isolation of early/sorting endosomes and demonstrate the application of the approach for analysis of endosomal proteomes and lipidomes, and for analysis of APP processing to A beta via beta and gamma-Secretases. Degradation and recycling of plasma membrane proteins occurs via the endolysosomal system, wherein endosomes bud into the cytosol from the plasma membrane and subsequently mature into degradative lysosomal compartments. While methods have been developed for rapid selective capture of lysosomes (Lyso-IP), analogous methods for isolation of early endosome intermediates are lacking. Here, we develop an approach for rapid isolation of early/sorting endosomes through affinity capture of the early endosome-associated protein EEA1 (Endo-IP) and provide proteomic and lipidomic snapshots of EEA1-positive endosomes in action. We identify recycling, regulatory and membrane fusion complexes, as well as candidate cargo, providing a proteomic landscape of early/sorting endosomes. To demonstrate the utility of the method, we combined Endo- and Lyso-IP with multiplexed targeted proteomics to provide a spatial digital snapshot of amyloid precursor protein (APP) processing by beta and gamma-Secretases, which produce amyloidogenic A beta species, and quantify small molecule modulation of Secretase action on endosomes. We anticipate that the Endo-IP approach will facilitate systematic interrogation of processes that are coordinated on EEA1-positive endosomes.Y

Deficiency of the frontotemporal dementia gene GRN results in gangliosidosis

Haploinsufficiency of GRN causes frontotemporal dementia (FTD). The GRN locus produces progranulin (PGRN), which is cleaved to lysosomal granulin polypeptides. The function of lysosomal granulins and why their absence causes neurodegeneration are unclear. Here we discover that PGRN-deficient human cells and murine brains, as well as human frontal lobes from GRN-mutation FTD patients have increased levels of gangliosides, glycosphingolipids that contain sialic acid. In these cells and tissues, levels of lysosomal enzymes that catabolize gangliosides were normal, but levels of bis(monoacylglycero)phosphates (BMP), lipids required for ganglioside catabolism, were reduced with PGRN deficiency. Our findings indicate that granulins are required to maintain BMP levels to support ganglioside catabolism, and that PGRN deficiency in lysosomes leads to gangliosidosis. Lysosomal ganglioside accumulation may contribute to neuroinflammation and neurodegeneration susceptibility observed in FTD due to PGRN deficiency and other neurodegenerative diseases

Architecture of the human interactome defines protein communities and disease networks

The physiology of a cell can be viewed as the product of thousands of proteins acting in concert to shape the cellular response. Coordination is achieved in part through networks of protein-protein interactions that assemble functionally related proteins into complexes, organelles, and signal transduction pathways. Understanding the architecture of the human proteome has the potential to inform cellular, structural, and evolutionary mechanisms and is critical to elucidation of how genome variation contributes to disease1–3. Here, we present BioPlex 2.0 (Biophysical Interactions of ORFEOME-derived complexes), which employs robust affinity purification-mass spectrometry (AP-MS) methodology4 to elucidate protein interaction networks and co-complexes nucleated by more than 25% of protein coding genes from the human genome, and constitutes the largest such network to date. With >56,000 candidate interactions, BioPlex 2.0 contains >29,000 previously unknown co-associations and provides functional insights into hundreds of poorly characterized proteins while enhancing network-based analyses of domain associations, subcellular localization, and co-complex formation. Unsupervised Markov clustering (MCL)5 of interacting proteins identified more than 1300 protein communities representing diverse cellular activities. Genes essential for cell fitness6,7 are enriched within 53 communities representing central cellular functions. Moreover, we identified 442 communities associated with more than 2000 disease annotations, placing numerous candidate disease genes into a cellular framework. BioPlex 2.0 exceeds previous experimentally derived interaction networks in depth and breadth, and will be a valuable resource for exploring the biology of incompletely characterized proteins and for elucidating larger-scale patterns of proteome organization