Navigation Links
Media highlights in the November issues of Biophysical Journal
Date:10/31/2007

Bethesda, MD - The November 1st and November 15th issues of Biophysical Journal, published by the Biophysical Society, are now available online. Topics of interest include voltage-gated potassium channels that could payoff in synthetic drug design, the absence of large lipid rafts in cells, and the structure of a Na+/H+ antiporter dimmer.

Volume 93, Issue 9, November 1, 2007

Dynamics of the Kv1.2 voltage-gated K+ channel in a Membrane Environment
Vishwanath Jogini, University of Chicago and Benoit Roux, University of Chicago

Keywords: arginine; electrostatics; free energy; membrane voltage; phospholipid; salvation

Using powerful computers at Argonne National Laboratory, scientists have taken a step closer to understanding how voltage-gated potassium channels work. Vishwanath Jogini and Benot Roux, researchers in the University of Chicagos Institute of Molecular Pediatric Science, used the large-scale computers in Argonnes Laboratory Computing Resource Center to conduct simulations of the channels in mammalian cells.

The features revealed by these computer simulations could lead to medical breakthroughs in synthetic drug design.

Specifically, Jogini and Roux produced molecular dynamic simulations of a detailed atomic model of the Kv1.2 voltage-gated potassium channel in an explicit membrane using the crystallographic x-ray structure determined by Rod MacKinnon (Rockefeller University) and his collaborators in 2005.

A long-term endeavor of biophysical research is to advance our understanding of these proteins and predict their function. The voltage-gated channels regulate the generation and spread of electrical signals in neurons, muscles, and other excitable cells. These minuscule electrical signals carry nerve impulses and control muscle contractions.

In humans, malfunction of these channels can result in neurological or cardiovascular diseases, such as cardiac arrhythmia.

Why are lipid rafts not observed in vivo?
Arun Yethiraj, University of Wisconsin and James C. Weisshaar, University of Wisconsin

Keywords: membrane proteins; phase transition; rafts

The cell membrane consists of many types of lipid and protein molecules. Some years ago the existence of lipid rafts, domains enriched in particular lipid molecules, was postulated. Many functions of the cell, including transport of matter from the outside (endocytosis) and signaling, during which specific proteins are gathered in a small area, have been attributed to rafts. The very existence of rafts in live cells, however, is hotly debated and direct evidence of rafts in vivo is sparse. While large rafts are readily observed in artificial membranes, attempts to observe analogous domains in live cells place an upper limit of 5 nanometers on their size.

In this paper Yethiraj and Weisshaar propose a new idea for why large rafts might not be present in cells. They suggest that proteins that span the membrane act as immobile obstacles, and show that the presence of these obstacles limits the size of lipid domains that can be formed. The presence of obstacles at only 5-10% by area suppresses the formation of large domains seen in artificial membranes. The structural and spatial heterogeneity of the membrane thus plays a crucial role in its biophysical properties.


Volume 93, Issue 10, November 15, 2007

High-resolution structure of a Na+/H+ antiporter dimer obtained by pulsed EPR distance measurements


Daniel Hilger, LMU Munich; Yevhen Polyhach, University of Konstanz; Etana Padan, Hebrew University of Jerusalem Heinrich Jung, LMU Munich and Gunnar Jeschke, University of Konstanz

Keywords: distance distribution; electron electron double resonance; membrane protein; protein-protein interaction; rotamer library; transporter

Our current knowledge about the molecular basis of life mainly stems from the determination of structures of the molecules of life, for instance proteins, DNA, and RNA. However, living cells largely function through the formation of short-lived complexes between such molecules, and in many cases such complexes are not accessible to existing approaches for structure determination. We introduce a new, broadly applicable approach that is based on distance measurements in the nanometer range between sites in the component molecules by pulsed electron paramagnetic resonance spectroscopy. This approach can provide highly resolved structures of biomacromolecular complexes if the structures of the components are known beforehand. It is applied to a dimer of the membrane transport protein NhaA, which is responsible for regulation of the intracellular pH in cells of Escherichia coli. Since the function of NhaA critically depends on dimerization, the dimer structure provides new insight into the mechanism of ion transportation through cell membranes by this protein.


'/>"/>

Contact: Ellen R. Weiss
eweiss@biophysics.org
301-634-7176
Biophysical Society
Source:Eurekalert

Related biology news :

1. Gene sequencing explains bioremediation bug
2. FDA Warns Consumers Not to Use Home-Use Diagnostic Kits Marketed by Globus Media
3. Activation of thermoreceptors mediates raw garlics burning pungency
4. A hope for oil spill bioremediation
5. Leading scientists rank endangered dolphins, porpoises most in need of immediate action
6. Several minute intermediate stage in virus-cell fusion discovered; opportunity for drug development
7. HIV accessory protein disables host immunity via receptor-protein intermediary
8. New journal article urges use of animal serum-free media for growing live cells
9. miRNA-mediated silencing of mRNAs
10. Endosome-mediated signaling in plants
11. New book highlights worlds borderless conservation areas
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:11/29/2016)... Nov. 29, 2016   Neurotechnology , ... object recognition technologies, today released FingerCell 3.0, ... recognition solutions that run on low-power, low-memory ... using less than 128KB of memory, enabling ... that have limited on-board resources, such as: ...
(Date:11/24/2016)... 2016 Cercacor today introduced Ember TM ... non-invasively measure hemoglobin, Oxygen Content, Oxygen Saturation, ... Rate in approximately 30 seconds. Smaller than a smartphone, ... access to key data about their bodies to help ... Hemoglobin carries oxygen to muscles. When ...
(Date:11/21/2016)... 21, 2016   Neurotechnology , a provider ... today announced that the MegaMatcher On Card fingerprint ... for the NIST Minutiae Interoperability Exchange (MINEX) ... mandatory steps of the evaluation protocol. ... test of fingerprint templates used to establish compliance ...
Breaking Biology News(10 mins):
(Date:12/9/2016)... New York , December 9, 2016 ... states that the top five players in the  Global ... 62.7% in the overall market in 2015. Players such ... Perkin Elmer have remained dominant in the global market ... efforts to ensure product innovation. Product upgrades and timely ...
(Date:12/8/2016)... 8, 2016  The Board of Directors of the ... Western Pennsylvania,s only pure life sciences investment ... with the succession plan developed by the Nominating and ... James (Jim) F. Jordan is selected to ... John W. Manzetti , who is elected to the ...
(Date:12/8/2016)... , December 8, 2016 AskLinkerReports.com ... comprehensive analysis, titled Global Amyloglucosidase Industry 2016 Market Research Report. ... application, and industry chain overview are all covered in the ... analysis, and investment return analysis of the Amyloglucosidase industry. ... , , ...
(Date:12/8/2016)... (PRWEB) , ... December 08, 2016 , ... ... the FrontPanel SDK that provide essential device-to-computer interconnect using USB or PCI Express, ... require FrontPanel support. The FOMD-ACV-A4 is a small, thin, SODIMM-style module that fits ...
Breaking Biology Technology: