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  • Research identifies 3D structure of key nuclear pore building block | Newswire
    Brian T Chait and Michael P Rout suggested in a 2004 paper in PLoS Biology that both the NPC and vesicle coats which contain similar protein folds evolved from ancient membrane coating proteins that stabilized these primordial internal membranes So far it s been unclear how these ancient folds work in the nuclear pore complex Kampmann says Now we can see that the α solenoid folds form long flexible arms and hinges that end in the more compact globular β propellers The same architectural principle is found in clathrin a common component of vesicle coats In research to be published Sunday in Nature Structural and Molecular Biology Kampmann isolated and purified samples of the most fundamental building block of the NPC known as the Nup84 complex which is composed of seven proteins The entire NPC enormous by molecular standards consists of 30 different kinds of proteins Focusing on the Nup84 complex Kampmann used an electron microscope EM to take thousands of images of the complex in different states or conformations which could reflect a role in the expansion and contraction thought to facilitate the passage of variously sized molecules through the NPC By computationally averaging these many different views he reconstructed the first three dimensional models of the Nup84 complex Finally based on prior work in the Blobel lab using x ray crystallography to determine the exact atomic structure of individual proteins in the Nup84 complex he plugged these proteins snugly into the EM structure Because the nuclear pore complex is probably too big and flexible to determine its entire atomic structure by x ray crystallography I think this three dimensional EM approach could be a big help in solving the whole thing Kampmann says It allows us to put the crystal structures that we do have in context Kampmann

    Original URL path: http://newswire.rockefeller.edu/2009/06/07/research-identifies-3d-structure-of-key-nuclear-pore-building-block/ (2016-02-13)
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  • Martin Kampmann | Newswire
    an unfolding picture of cellular evolution that shows a common architecture for the nuclear pore complex NPC and the vehicles that transport material between different parts of the cell Scientists have for the first time glimpsed in three dimensions the subcomplex of the NPC that is its key building block More Tags Günter Blobel Martin Kampmann nuclear pore complex Search for Categories Science News Awards and Honors Campus News Grants

    Original URL path: http://newswire.rockefeller.edu/tag/martin-kampmann/ (2016-02-13)
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  • New model of a nuclear pore complex is based on crystal structure of its key component | Newswire
    has proposed a new molecular model of the nuclear pore Visualizing the nuclear pore complex is a particularly tricky endeavor It s such a large pliant structure that traditional methods just don t work So researchers have had to get creative Just a month ago two Rockefeller professors published the first complete model of a nuclear pore complex created through a combination of biochemical spectrometry and computer modeling techniques Blobel s team Kuo Chiang Hsia Peter Stavropoulos Blobel and André Hoelz used an approach that was quite different x ray crystallography to visualize a core piece of the pore and determine how it bound to a neighboring complex then puzzle solving to deduce how the rest of the structure fit together In the end the researchers results differed too But the new findings were consistent with research published by the Blobel lab last spring which proposed a ring like arrangement of sliding subunits Using the high resolution structures they ve uncovered Hoelz says the lab is working to build a model of the nuclear pore complex that s constructed piece by piece He and Blobel found that their complex called Sec13 Nup145C crystallized into two distinct shapes that came together to form a bent rod From there they devised a molecular architecture for the pore that consists of eight of these rods placed vertically linking four stacked rings of alternating protein complexes in a pattern akin to houndstooth Hoelz a research associate and Blobel John D Rockefeller Jr Professor and a Howard Hughes Medical Institute investigator propose that this structure may represent one of the four concentric cylinders that according to their previous research may make up the core of the nuclear pore Clearly more work will be required to test these two proposals Blobel says The nuclear pore is

    Original URL path: http://newswire.rockefeller.edu/2008/01/15/new-model-of-a-nuclear-pore-complex-is-based-on-crystal-structure-of-its-key-component/ (2016-02-13)
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  • Andre Hoelz | Newswire
    nuclear pore complex Inside the cell nucleus DNA is transcribed into RNA that then leaves the nucleus and binds to the cell s ribosomes where it is translated into proteins But in order to get to the ribosome the RNA must pass through a relatively large complicated and little understood structure called the nuclear pore complex Researchers at The Rockefeller University have a new model for the gatekeeper to the nucleus and have discovered the crystal structure of a protein pair that backs it up More Tags Andre Hoelz nuclear pore complex August 11 2008 Science News Researchers solve structure of an enzyme vital for DNA repair As freshly made DNA coils into a chromosome cells recognize DNA damage in need of repair Now a new study shows how an enzyme known as Rtt109 which creates slack in the coils in order to allow the cell access to fix the errors is regulated More Tags Andre Hoelz DNA repair January 15 2008 Science News New model of a nuclear pore complex is based on crystal structure of its key component In the second nuclear pore study to come out of Rockefeller University in as many months researchers have determined the crystal structure of one of the pore s main components Using that shape as their base they propose an overall structure for the circular pore rings of alternating protein complexes that fit together like two sides of a zipper More Tags Andre Hoelz Günter Blobel nuclear pore complex April 13 2007 Science News Building the nuclear pore piece by piece Because the nuclear pore is the only way in or out of the nucleus the cell is in dire straits when the pore malfunctions as in forms of leukemia where nuclear pore complex proteins are mutated Two new structural renderings

    Original URL path: http://newswire.rockefeller.edu/tag/andre-hoelz/ (2016-02-13)
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  • Building the nuclear pore piece by piece | Newswire
    much of the cell s machinery and can communicate with the outside environment The core of the structure is a symmetrical tunnel each end of which is studded with an assortment of gatekeeper proteins These gatekeeper proteins there are about 30 different kinds found in various combinations join to form some of the largest protein complexes within any cell The sheer size of the nuclear pore makes the task of isolating its components and studying their functions daunting To tackle this problem members of Günter Blobel s Laboratory of Cell Biology have designed an approach where the nuclear pore complex is broken into smaller more manageable pieces whose structures can be solved using x ray crystallography The entire atomic model of the nuclear pore complex could be built like a puzzle by fitting the smaller structures together However when Ivo Melcák a research associate and André Hoelz a postdoc looked carefully at the crystal structure of two of these components mammalian proteins called Nup58 and Nup45 they were surprised by what they found the two proteins in four different conformations Crystallography usually shows a protein or proteins in their most common state so how could there be four The researchers took a closer look at the amino acids that were interacting on each of the two proteins On each side of the two proteins they saw a long line of charged residues that could interact like a series of magnets The two proteins could loosely associate with each other in any of a variety of ways with no one way more common than any other Crystallization is like taking photographs says Hoelz trapping the protein in a single state Our crystals show these proteins being very dynamic and moving around In fact when they arranged the different snapshots one after another like a flipbook they saw that the Nup58 45 proteins were actually sliding back and forth along each other The four conformations they had seen were different positions along the slide The scientists calculated that one pair of proteins could slide a large distance Nup58 and Nup45 are also two of the most abundant proteins in the nuclear pore complex they line much of the central channel If they each slide a long way it would suggest that the nuclear pore could change the size of its central channel drastically like a camera aperture In this way the pore could accommodate both small and large cargo passing through the channel It is the first time this type of movement has ever been documented During this time Hoelz was also working with Johanna Napetschnig a graduate student in Blobel s lab to crystallize a different nuclear pore complex protein Nup214 The two researchers compared their structure of mammalian Nup214 to the structure of the same protein in yeast and saw for the first time how different these homologous proteins can be in how their core is decorated The different decorations of the protein allow for many types of regulation in

    Original URL path: http://newswire.rockefeller.edu/2007/04/13/building-the-nuclear-pore-piece-by-piece/ (2016-02-13)
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  • The protein’s in the mail | Newswire
    misfirings in the protein transport system known as protein secretion are intolerable to the cell says Schwartz It is essentially impossible for the cell to survive major errors in this process which occurs at the most basic level necessary for survival Switch campaign The life of a protein begins in a tiny cellular factory called a ribosome There a protein a chain of amino acids linked together in a specific configuration is manufactured on a cellular assembly line Once synthesized the new protein must be shipped to the address where it is needed One of the major protein transport systems in eukaryotic organisms organisms whose cells feature a structurally discrete nucleus and other well developed subcellular compartments has long been known to principally involve three molecular switches called GTPases One of these GTPases known as SRP 54 part of a larger complex called the Signal Recognition Particle composed of six proteins and an RNA molecule works in concert with GTPases SR alpha and SR beta the subunits of the two part SRP receptor Schwartz s structure formed when the two molecular subunits are bound establishes that SR beta must be switched on in order to be bound by the other subunit SR alpha and form the heterodimer This new information clears up a widely held misconception in the field of protein transport according to Schwartz Schwartz explains that without a clear understanding of SR beta s function most scientists who study protein transport in cells incorrectly believed that SR alpha and beta were always and only in complex that is joined as one functional unit in the cell The function of the two subunits of the SRP receptor was a mystery adds Blobel Until now no one really knew what the SR beta switch was good for Neither rain nor sleet keeps GTPases from appointed rounds Depending upon their individual functions freshly manufactured proteins are transported to different destinations as they exit the ribosome Some stay in the cell some such as insulin and other hormones leave the cell others must make their way into a cell organelle called the endoplasmic reticulum ER where they may end their journey or continue on toward a role in one of the eukaryotic cell s several other membranes Like postal workers at different checkpoints along a delivery route SRP 54 SR alpha and SR beta work together to ensure delivery to the proper address of proteins destined to be exported out of the cell or to do jobs in the cell s membrane This address is a channel located in the ER through which the proteins travel Cells to be exported out of the cell are further processed and packed into membrane vesicles that eventually fuse with the cell membrane to release the protein outside the cell Proteins with jobs to do in the membrane itself enter the channel and from there are inserted into the membrane probably through a side opening in the channel Schwartz and Blobel hypothesize Blobel s Nobel research

    Original URL path: http://newswire.rockefeller.edu/2003/03/27/the-proteins-in-the-mail/ (2016-02-13)
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  • protein | Newswire
    mailbox somewhere in the city Each day every cell of the human body manufactures millions of proteins which it also must continually sort and route to their final destinations within the cell Only when a protein has reached its destination can it do its assigned work More Tags Günter Blobel protein SRP Search for Categories Science News Awards and Honors Campus News Grants Gifts Topics Video Archive 2015 2014 2013

    Original URL path: http://newswire.rockefeller.edu/tag/protein/ (2016-02-13)
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  • NYC pilot study pushes Human Genome Project toward cures for disease | Newswire
    starting point from which to ask questions about other biological processes While genes carry the blueprints for life proteins perform the vital functions necessary for life to exist Proteins long chains of building blocks called amino acids that fold into compact but flexible shapes carry out virtually all of life s essential functions through chemical reactions Their structures are determined by the order of the amino acids which is prescribed by the genes carrying instructions for making the proteins In architecture it is said that form follows function you begin with a purpose that dictates the style and shape of a structure Sali says In structural biology function follows form because the shape of a protein is the very definition of what task it performs It would take decades to determine every three dimensional structure of every protein encoded by the human genome and this undertaking would yield many of the same shapes over and over Because of this the scientists suggest focusing primarily on disease related proteins As the scientists explained in a commentary published in the journal Nature Genetics focusing on these likely suspects will bring a quicker payoff Such an approach is possible only through dramatic advances in computational biology most notably specially designed software that finds all the protein coding regions in a genome and also allows researchers to use structural and biochemical information to understand protein function The scientists say that choosing medically relevant protein targets will provide benefits whether its folds are new i e different from those in other proteins already solved or old and whether its function is already known or is unknown They also think choosing these targets will have important consequences for disease and patient oriented research First any newly determined structure will be of immediate relevance to academic and or industrial research teams studying that biological system Second by publicizing target lists on the Internet the structural genomics pilot studies could generate scientific interest and expertise and attract suggestions for additions to their respective target lists Third the pilot studies will be able to serve as an important resource for distribution of tools and reagents for research One can imagine that some future NIH grant applications would include both a request for funds and a request for a supply of a particular purified protein deposited in a centralized cold storage facility Sali says The discovery of the double helical structure of DNA by Watson and Crick in the 1950s ushered in the modern field of molecular biology and since then molecular and cell biologists have become proponents of the gene product theory of human disease Instead of examining microbial invaders for example the biomedical research community studies the consequences of introducing foreign proteins such as fungal bacterial and viral virulence factors into humans or the results of genetic mutations that disrupt the function of normal genes This molecular view of disease has contributed to the importance of studies of the three dimensional structure of proteins using techniques such as

    Original URL path: http://newswire.rockefeller.edu/2000/02/24/nyc-pilot-study-pushes-human-genome-project-toward-cures-for-disease/ (2016-02-13)
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