Navigation Links
Tug of war in the cells

This release is available in German.

Transport processes in the cells of our body resemble the transport of goods on the roads. Molecular motors, which are special protein molecules, act as trucks. They carry the cellular cargo on piggy-back and transport it along microtubules, which are the roads of the cell. However, the molecular transporters are a billion times smaller than trucks and can only move as far as the beginning or end of the microtubule, depending on their type. They have to fight their way through a crowd that is more like a busy pedestrian area than a motorway, and also have to compete with motors that want to move in the opposite direction, as scientists at the Max Planck Institute of Colloids and Interfaces in Potsdam have now discovered in a computer simulation.

Several motors are always involved in the tug-of-war over a cargo - for example, some of the kinesin type and some of the dynein type. The kinesin motors move to the end of the microtubule that biologists call the positive end, while the dynein motors move to the minus end. The findings of the Potsdam-based scientists show that the stronger motor team determines the direction in which the cargo is moved. It involves a tug-of-war where opposing motors break off from the microtubule. It was previously assumed that there was a system of coordination that allowed for only one team of motors; it was believed this alternated between one team and the other.

"The tug-of-war is the simplest imaginable mechanism," says Melanie Mueller, one of the scientists involved in the project. "But it is possible, if you consider the properties of the individual motors measured experimentally. They produce a strong non-linear reaction when they are pulled." A motor from the losing team is subject to a strong force and is quickly removed from the microtubule. The remaining motors must then take the force of the winning team alone and are also removed even more quickly. In a domino effect, the losing motors concede and are removed from the microtubule until no others remain. The winning team is then able to transport the cargo quickly, unopposed. "However, the cell does not leave it to chance to ensure that the cargo arrives at its destination. Regulatory proteins probably intervene," says Melanie Mueller.

Researchers into the transport of fat particles in Drosophila embryos examined whether her model applied in reality. It is actually explained by experimental observations that took place previously on the transport mechanism. A cargo in a microtubule does not move directly from one end to the other. It is constantly pulled back in the opposite direction. The losing motors can, however, occasionally remove the winning ones from the microtubule as heat sometimes blows the winning motors away. The cargo particles therefore move in both directions.

"This bi-directional transport process is very flexible," explains Melanie Mueller. It can change direction if the cargo passes its destination or change the speed of the transport. The tug-of-war mechanism, where the winning team pulls the opposing motor team as well as the cargo through the cell, also solves another logistical problem in the cell. It always carries the motors to the end of the microtubule from which they are able to move, preventing an accumulation of motors of one kind at their respective destination.

"Despite the simple mechanism, a cargo particle transported by two motor teams reveals very complex motility behavior," said Melanie Mueller. There are seven different types of motility behavior. These are various combinations of movements to the positive and minus end as well as pauses to which the cargo particles can be subjected. The probability of movement in a certain direction or stopping, and the time lapses between the changes of direction, depend heavily on the properties and the number of the motors involved. The cell uses these to direct the cargo transport. If a team of motors is pulled harder or faster, the cargo moves in the minus instead of the positive direction or stops.

"The simple and efficient tug-of-war mechanism could be used for the transport in micro-laboratories on chips," relates Melanie Mueller. In the same way as with the biological model, teams of motors can transport certain molecules to specific reaction locations on the chip and then also bring back the reaction product. "Our quantitative tug-of-war theory allows motor properties to be optimized for this purpose," according to Mueller.


Contact: Melanie J.I. Mueller

Related medicine news :

1. Scientists successfully awaken sleeping stem cells
2. How is H pylori adhesion to gastric cells associated with MUC1 mucin VNTR size?
3. Post brain injury: New nerve cells originate from neural stem cells
4. Blood Stem Cells Originate in the Placenta
5. Einstein researchers genetically engineer immune cells into potent weapons for battling HIV
6. Fugitive cancer cells can be blocked by stopping blood cells that aid them
7. Cell recycling protects tumor cells from anti-cancer therapy
8. UCLA researchers find blood stem cells originate and are nurtured in the placenta
9. Protein in Human Embryonic Stem Cells Controls Malignant Tumor Cells
10. Greatest Satisfaction Preserving Granddaughters Cord Blood Stem Cells
11. Neural progenitor cells as reservoirs for HIV in the brain
Post Your Comments:
Related Image:
Tug of war in the cells
(Date:11/27/2015)... , ... November 27, 2015 , ... ... November 27th edition of USA Today in Atlanta, Dallas, New York, Minneapolis, South ... 750,000. The digital component is distributed nationally, through a vast social media strategy ...
(Date:11/27/2015)... ... ... A simply groundbreaking television series, "Voices in America", which is hosted by Hollywood legend, ... that are presently affecting Americans. Dedicated to providing the world with a wide variety ... consumers focus on, one episode at a time. , In the latest installment ...
(Date:11/27/2015)... (PRWEB) , ... November 27, 2015 , ... Dr. ... Medical Associates, Inc. and Dr. Tucker Bierbaum with Emergency Medicine at St., ... observed that both STEMI and Sepsis conditions present in similar ways and require time-critical ...
(Date:11/26/2015)... (PRWEB) , ... November 26, 2015 , ... ... a real-time eReferral system for diagnostic imaging in the Waterloo region. Using the ... and Nuclear Medicine tests directly from their electronic medical record (EMR) without the ...
(Date:11/26/2015)... , ... November 26, 2015 , ... ... medical opinion process, participated in the 61st annual Employee Benefits Conference. The Employee ... took place Sunday, November 8th through Wednesday, November 11th, 2015. The conference was ...
Breaking Medicine News(10 mins):
(Date:11/25/2015)... 2015  The total global healthcare industry is expected to ... Latin America has the highest projected growth ... Japan ), is second with growth projected at ... increased healthcare expenditure. In 2013-2014, total government funded healthcare was ... 2008-2009 to 41.2% in 2013-2014. In real terms, out of ...
(Date:11/25/2015)... , Nov. 25, 2015  The American ... and Gynecologists (ACOG), and the March of Dimes ... Protecting Our Infants Act of 2015 ... number of newborns born exposed to drugs, such ... the bill,s introduction, all three organizations have worked ...
(Date:11/25/2015)... AAIPharma Services Corp./Cambridge Major Laboratories, Inc. ... $15.8  Million to expand its laboratories and global ... The expansion will provide additional office space and ... of the pharmaceutical and biotechnology markets. ... up to 40,000 square feet of expanded development ...
Breaking Medicine Technology: