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  • David C. Gadsby | Newswire
    researchers decipher the shape of a sodium potassium ion pump The sodium potassium pump is one of the most prevalent proteins on a cell s surface and is responsible for collecting ions on one side of the cell membrane and pushing them to the other Two new papers by Rockefeller University researchers provide a more nuanced picture of the pump s interior channel as well as a more precise target for future antacid drugs More Tags David C Gadsby ion pump May 27 2005 Awards and Honors Rockefeller University scientist elected fellow of Royal Society Rockefeller University s David Gadsby Ph D was elected a fellow of the Royal Society for his research into how ion transporters function and specifically for furthering our understanding of the origins of cystic fibrosis More Tags David C Gadsby Royal Society of London January 21 2003 Science News Hardworking sodium potassium pump fundamentally similar to free flowing ion channel Right now in your body tiny pumps in the fatty membranes surrounding all your cells are hard at work pushing select charged ions such as sodium potassium or calcium through those membranes Like a water pump in a high rise apartment building overcoming the force

    Original URL path: http://newswire.rockefeller.edu/tag/david-c-gadsby/ (2016-02-13)
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  • ion pump | Newswire
    scientists have uncovered the road map that those ions follow across the cell membrane More Tags David C Gadsby ion pump October 25 2006 Science News Rockefeller University researchers decipher the shape of a sodium potassium ion pump The sodium potassium pump is one of the most prevalent proteins on a cell s surface and is responsible for collecting ions on one side of the cell membrane and pushing them to the other Two new papers by Rockefeller University researchers provide a more nuanced picture of the pump s interior channel as well as a more precise target for future antacid drugs More Tags David C Gadsby ion pump January 21 2003 Science News Hardworking sodium potassium pump fundamentally similar to free flowing ion channel Right now in your body tiny pumps in the fatty membranes surrounding all your cells are hard at work pushing select charged ions such as sodium potassium or calcium through those membranes Like a water pump in a high rise apartment building overcoming the force of gravity to move water up to a tank on its roof these ion pumps work against electrochemical gradients to transport ions from one side of the membrane to the

    Original URL path: http://newswire.rockefeller.edu/tag/ion-pump/ (2016-02-13)
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  • potassium | Newswire
    such as sodium potassium or calcium through those membranes Like a water pump in a high rise apartment building overcoming the force of gravity to move water up to a tank on its roof these ion pumps work against electrochemical gradients to transport ions from one side of the membrane to the other More Tags David C Gadsby ion channel ion pump potassium Search for Categories Science News Awards and

    Original URL path: http://newswire.rockefeller.edu/tag/potassium/ (2016-02-13)
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  • Another Transmembrane Protein Structure Solved by Rockefeller Scientists | Newswire
    biomedical solutions to the known impairments of ion channels will improve human health considerably The channels also called transmembrane proteins ingeniously shepherd vital molecules across cellular and intracellular membranes keeping surrounding structures and biochemistry intact Each kind of ion channel has selective features that permit only appropriately sized and charged molecules to travel to their destination in the cell or outside of it A distinctive hourglass shape seen for the first time in MacKinnon and colleagues research defines the chloride channel and provides a striking contrast to the aqueous pyramid shaped cavity of the potassium ion channel The revelation of the hourglass shape brings new insights to the mechanism by which a chloride ion is stabilized inside the channel MacKinnon and his colleagues research also greatly clarifies existing biochemical analyses of the chloride channel begun 20 years ago In a way the potassium channel is very brash while the chloride channel is more subtle says MacKinnon By working on both channels we can start to see some themes that nature uses The ClC Chloride Channel Chloride channels sit at the boundary junctures of a cell allowing negatively charged ions called anions to pass through the membrane into the cell cytoplasm or intra cellular organelles Once through the channel the chloride ions carry out important work such as regulating electrical impulses and stabilizing the resting membrane potential of the cell The human genome contains at least nine different chloride ion channels The chloride channel s hourglass shape helps overcome the energy barrier between the outside of a cell and its internal environment report MacKinnon and colleagues Being charged ions would rather be in water than in an oily membrane says MacKinnon Nature has to have a mechanism to get the ion across the cell membrane The chloride ion s negative charge requires different conditions and a different structural configuration than the potassium ion s positive charge Part of this structural difference lies in the channel s pore composition feature The two bacterial chloride channels pictured in the Nature paper from salmonella typhimurium and Escherichia coli are homodimers meaning they have two identical subunits composing the overall structure Each subunit has its own pore for chloride ions to pass through The potassium ion channel by contrast is a tetramer meaning its overall structure comprises four identical or similar subunits These channels have only one pore encircled by the four parts In the potassium channel we saw that nature used the alpha helices to accomplish a partial negative charge says MacKinnon In the chloride channel nature flipped the helices around to put the partial positive end of the helix near the chloride ion It s very beautiful The gating mechanism of the chloride channel also is unique The crystallographic images from MacKinnon s group reveal a glutamate side chain to the structure that potentially blocks the ion pathway For the first time insight to the chloride channel s gating mechanism is revealed As with MacKinnon and his colleagues work on the potassium ion

    Original URL path: http://newswire.rockefeller.edu/2002/01/17/another-transmembrane-protein-structure-solved-by-rockefeller-scientists/ (2016-02-13)
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  • Rockefeller Researcher Roderick MacKinnon Receives 1999 Lasker Award | Newswire
    of the ten biggest science stories of the year MacKinnon modestly called his research as basic as it gets but other scientists strongly praised his work A remarkable accomplishment proclaimed Armstrong who reviewed MacKinnon s paper in the same issue of Science It is a dream come true for biophysicists The transfer of potassium ions across cell membranes has long been understood as an essential activity for many life sustaining functions The proper balance of these ions is essential for fundamental operations such as the transmission of nerve impulses throughout the body and brain But until MacKinnon captured an image of the channel it was not well understood how the process actually worked Shaped like tiny doughnuts floating in oil ion channels perform the dual functions of gateway and gatekeeper The holes in the doughnut form the gateway through which the ions flow However these holes or pores are endowed with special properties that enable different channel proteins to be selective as to which ions they allow passage MacKinnon sought to understand the structure of the protein and the answers to two compelling questions What do these channels look like And how are they able to allow passage of potassium ions while blocking other ions that are similar Using electrophysiological and biochemical approaches MacKinnon studied the interaction of the potassium channel with a specific toxin derived from scorpion venom and figured out that the toxin blocked the flow of ions by sitting directly on the pore of the channel He then exploited the toxin to analyze the subunit structure the moving gates and the ion conduction pathway of potassium channels MacKinnon calls the design of the potassium ion channel protein elegant in its simplicity The balance of electrical forces and chemical bonds inside the protein not only send potassium ions

    Original URL path: http://newswire.rockefeller.edu/1999/09/26/rockefeller-researcher-roderick-mackinnon-receives-1999-lasker-award/ (2016-02-13)
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  • Ion flow through membrane channels is dictated by particle size | Newswire
    body they must maintain an electrical disparity between the inside of the cells and their surrounding environment Although scientists have long known that ion channels are responsible for preserving this disparity they had questions about how the channels discern the difference between ions like sodium and potassium which both carry a single positive charge In a paper in PLoS Biology Rod MacKinnon John D Rockefeller Jr Professor and head of the Laboratory of Molecular Neurobiology and Biophysics demonstrates that potassium channels discriminate among ions based on their size Potassium ions are slightly bigger than sodium ions with a radius about one third larger and that greater volume means they have less charge distributed across their surface Potassium takes more space but it also diffuses its charge over a bigger area so potassium has lower charge density says Steve Lockless a postdoctoral fellow in the MacKinnon lab and the paper s first author To find out whether the potassium channel relies on size or its charge density to identify potassium and exclude sodium Lockless MacKinnon and postdoctoral fellow Ming Zhou played a trick on it They separated potassium channels from the cell membranes and put them in a solution with barium an ion roughly the same size as potassium but with two positive charges about the same charge density as sodium If the channel recognized the charge density then we would not expect barium to bind to the potassium channel Lockless says But we found the opposite Barium bound to the potassium channel indicating to the researchers that the channel is detecting an ion s size Lockless and MacKinnon a Howard Hughes Medical Institute investigator conclude that while sodium ions may bounce around at the channel s opening they are too small and their charge too concentrated to press all the

    Original URL path: http://newswire.rockefeller.edu/2007/06/27/ion-flow-through-membrane-channels-is-dictated-by-particle-size/ (2016-02-13)
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  • Phospholipids in the cell membrane help regulate ion channels | Newswire
    in or out of the cell conveying messages from adjacent cells It s gating charges made up of the positively charged amino acid arginine that keep tabs on the electrical environment at the cell s surface and thereby control when and for how long the pore remains open Rockefeller University s Roderick MacKinnon who first published the structure of a voltage gated potassium channel known as KvAP three years ago has found that the channel s function is also controlled by lipids in the cell membrane The channel proteins are surrounded by lipids says Qiu Xing Jiang a postdoc in MacKinnon s lab and co first author We couldn t help thinking since you have positively charged arginines in the regulatory domains of the channels next to negatively charged phosphates in the heads of the phospholipids in the membrane wouldn t they form a really nice bonding pair So the immediate question was whether the lipids were interacting at all with the channel proteins Jiang along with Daniel Schmidt co first author and a graduate student in the MacKinnon lab made bilayers with non phospholipids that were either positively charged negatively charged or had no charge at all They then added KvAP channels and tested their function In each case KvAP wouldn t function says Schmidt Jiang and Schmidt then started adding back phospholipids to their membranes and the channel started to function again Then as they began to dilute out the phospholipids the channel became less and less functional The experiments all showed that it was the phosphate that made the difference As long as it is there the channel will work says Schmidt Further tests are needed to show whether this effect is due to a direct interaction between the positively charged arginine residues and the phosphate This

    Original URL path: http://newswire.rockefeller.edu/2007/02/16/phospholipids-in-the-cell-membrane-help-regulate-ion-channels/ (2016-02-13)
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  • Nobel Prize honors Rockefeller University scientist Roderick MacKinnon for revealing process of electrical signaling in humans and other living organisms | Newswire
    channel but also the chemical and voltage dependent mechanisms that control its opening and closing to allow potassium ions to move out of a cell The full range of activity of the latter of the three potassium ion channels the voltage dependent channel has been a puzzle for over 50 years since scientists Alan Hodgkin Andrew Huxley and Bernard Katz proposed a theory called the action potential The action potential explained how a nerve signal formed and moved throughout the body This theory based on two mathematical equations explained how cells are involved with moving a nerve signal along permeability which we now know is the open or closed positions of ion channels studding a cell s outer membrane impacts the positive or negative charge value of a cell s membrane and creates an environment conducive to moving a signal along a cell s surface The three scientists working in the 1950s suggested a feedback loop relating permeability and voltage one condition determines the next which in turn creates the first condition all over again Experimental scientists in the meantime have long understood how permeability sets the voltage of a cell membrane but until Rod MacKinnon came along no one ever understood how the voltage of a cell s membrane could determine whether ion channels were opened or closed Hodgkin and Huxley were awarded a Nobel Prize for their action potential theory in 1963 Today 40 years later MacKinnon shares the Nobel Prize and has wowed biologists by discovering how the electrical charge of a cell s membrane determines the open or closed position of an ion channel Our understanding of Hodgkin and Huxley s feedback loop is finally complete thanks to Rod MacKinnon Finding the inner beauty Other scientists steeped in molecular genetics have collaborated with an outstanding X ray crystallographer to solve protein structures MacKinnon exhibiting his typical independence and rigor instead became that crystallographer Ion channels also called integral or transmembrane proteins defy crystallographic visualization The problem is that these proteins naturally stud the walls of cells and because of their positioning and the role they play they are hydrophobic or water hating To form crystals the proteins must be isolated in the lab and many copies freed from their natural context must be produced in a water loving manner The other problem is that getting a protein to crystallize doesn t guarantee that it will diffract light properly Yufen Zhou Ph D a postdoctoral fellow in MacKinnon s laboratory says So many crystals look beautiful but they don t diffract well We always say it s an inner beauty that makes a protein diffract well If you re a crystal you have to have inner beauty And only X ray diffraction can tell if your crystal has inner beauty Crystals are important because by definition they contain a repeating pattern of a molecule within them The X ray diffraction from one molecule would not be significant enough to study confidently After carefully cultivating ion channel proteins

    Original URL path: http://newswire.rockefeller.edu/2003/10/08/nobel-prize-honors-rockefeller-university-scientist-roderick-mackinnon-for-revealing-process-of-electrical-signaling-in-humans-and-other-living-organisms/ (2016-02-13)
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