Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rhesus Proteins Transport Ions, not Gas

27.06.2014

Using artificial lipid vesicles, biochemists show how membrane proteins transport ammonium.

Do they carry the gas ammonia or the ammonium ion in their luggage? And is transport active or passive?


Proteins of the Amt family transport ammonium across the lipid membrane of the cell

(Quelle. Susana Andrade)

Biochemists have long speculate on the mechanistic details of the ammonium transport family of proteins (Amt), which include the Rhesus protein factors, known as the mammalian blood group system.

What was previously known is that Amt proteins extend across cellular membranes where they specifically transport the nitrogen into bacteria and plant cells, essential nutrient for their growth and survival. In mammals, Rhesus proteins regulate acid and ion balance in kidney and liver cells.

... more about:
»Biochemistry »Centre »Gas »NH4+ »PNAS »Phone »Rhesus »Transport »blood »protein »proteins »protons

A team of scientists led by Prof. Dr. Susana Andrade from the Institute of Biochemistry of the University of Freiburg and the Cluster of Excellence BIOSS Centre for Biological Signalling Studies has now determined the transport properties of Amt proteins with great precision on the basis of electrophysiology tests on artificial lipid systems.

The scientists cloned the membrane proteins from an archaea, a microorganisms that lives under extreme temperature conditions and isolate them. In 2005, the Freiburg researchers already threw light on the crystalline three-dimensional structure of a protein of this kind.

Now they have added the protein to a layer of lipid molecules, enabling them to measure the ion currents directly. The team discovered that a positive charge travels through the membrane: The membrane proteins do not transport the gas ammonia NH3 but rather the ammonium ion NH4+. The researchers published their findings in the journal Proceedings of the National Academy of Sciences of the USA.

“The results can, in a large part, be transferred to the Rhesus proteins from mammals,” says Andrade as Amt proteins bear a close resemblance to the Rhesus proteins found in humans. They are produced in the blood, in the kidney, and in the liver, where they regulate the intake of ammonium and thus the body’s pH.

The researchers tested three Amt proteins that are present in the bacteria and also determined the speed with which they allow ammonium to pass through the membrane. “In the future, we want to modify individual components of the transporter to improve our understanding of the exact molecular details involved” explains Andrade.

The scientific debate on Amt/Rh proteins stems from the difficulty of distinguishing between ammonia and ammonium in measurements, as the two molecules are transformed into each other in a continuous state of balance with protons. “Our in vitro method gives us a level of precision that finally allows us to draw valid conclusions concerning the transport process,” stresses the researcher.

Original publication: 
Tobias Wacker, Juan J. Garcia-Celma, Philipp Lewe, and Susana L. A. Andrade, Direct observation of electrogenic NH4+ transport in ammonium transport (Amt) proteins, PNAS 2014; published ahead of print June 23, 2014, doi:10.1073/pnas.1406409111

Contact:
Prof. Dr. Susana Andrade
Institute of Biochemistry
BIOSS Centre for Biological Signalling Studies
University of Freiburg
Phone: +49 (0)761/203-8719
E-Mail: andrade@bio.chemie.uni-freiburg.de

Katrin Albaum | Albert-Ludwigs-Universität Freiburg
Further information:
http://www.pr.uni-freiburg.de/pm/2014/pm.2014-06-27.57-en2

Further reports about: Biochemistry Centre Gas NH4+ PNAS Phone Rhesus Transport blood protein proteins protons

More articles from Life Sciences:

nachricht Protein scaffold
27.05.2015 | Okinawa Institute of Science and Technology (OIST) Graduate University

nachricht Seeing the action
27.05.2015 | University of California - Santa Barbara

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Advance in regenerative medicine

The only professorship in Germany to date, one master's programme, one laboratory with worldwide unique equipment and the corresponding research results: The University of Würzburg is leading in the field of biofabrication.

Paul Dalton is presently the only professor of biofabrication in Germany. About a year ago, the Australian researcher relocated to the Würzburg department for...

Im Focus: Basel Physicists Develop Efficient Method of Signal Transmission from Nanocomponents

Physicists have developed an innovative method that could enable the efficient use of nanocomponents in electronic circuits. To achieve this, they have developed a layout in which a nanocomponent is connected to two electrical conductors, which uncouple the electrical signal in a highly efficient manner. The scientists at the Department of Physics and the Swiss Nanoscience Institute at the University of Basel have published their results in the scientific journal “Nature Communications” together with their colleagues from ETH Zurich.

Electronic components are becoming smaller and smaller. Components measuring just a few nanometers – the size of around ten atoms – are already being produced...

Im Focus: IoT-based Advanced Automobile Parking Navigation System

Development and implementation of an advanced automobile parking navigation platform for parking services

To fulfill the requirements of the industry, PolyU researchers developed the Advanced Automobile Parking Navigation Platform, which includes smart devices,...

Im Focus: First electrical car ferry in the world in operation in Norway now

  • Siemens delivers electric propulsion system and charging stations with lithium-ion batteries charged from hydro power
  • Ferry only uses 150 kilowatt hours (kWh) per route and reduces cost of fuel by 60 percent
  • Milestone on the road to operating emission-free ferries

The world's first electrical car and passenger ferry powered by batteries has entered service in Norway. The ferry only uses 150 kWh per route, which...

Im Focus: Into the ice – RV Polarstern opens the arctic season by setting course for Spitsbergen

On Tuesday, 19 May 2015 the research icebreaker Polarstern will leave its home port in Bremerhaven, setting a course for the Arctic. Led by Dr Ilka Peeken from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) a team of 53 researchers from 11 countries will investigate the effects of climate change in the Arctic, from the surface ice floes down to the seafloor.

RV Polarstern will enter the sea-ice zone north of Spitsbergen. Covering two shallow regions on their way to deeper waters, the scientists on board will focus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International symposium: trends in spatial analysis and modelling for a more sustainable land use

20.05.2015 | Event News

15th conference of the International Association of Colloid and Interface Scientists

18.05.2015 | Event News

EHFG 2015: Securing health in Europe. Balancing priorities, sharing responsibilities

12.05.2015 | Event News

 
Latest News

Researchers develop intelligent handheld robots

27.05.2015 | Power and Electrical Engineering

"Hidden" fragrance compound can cause contact allergy

27.05.2015 | Health and Medicine

Supernovas help 'clean' galaxies

27.05.2015 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>