Proteins find their way with address label and guide

Feb 23, 2011

Most newly produced proteins in a cell need to be transported to the proper place before they can be put to work. For proteins to find their way, they have a built-in signal linked to them, a kind of address label. Moreover, they are helped by a particle that guides them to the cell membrane. In a new study published in the journal Nature Structural and Molecular Biology, researchers at Umea University in Sweden show how this interaction works.

Calculations indicate that each human cell contains roughly a billion . In other words, it's crowded inside the cell, and order must be maintained. What's more, newly generated proteins often need to be transported from the place they were produced to the place they are to perform their tasks. These proteins have a kind of address label, a signal sequence, that specifies what place inside or outside the cell they need to be transported to. This transport must function flawlessly if order is to be maintained in the cell, but also for the cell to be able to communicate with its surroundings. If a protein winds up in the wrong place, it can lead to serious disorders like .

The capacity to transport proteins in most cases is directly linked to the function of the SRP, the signal-recognizing particle. The SRP binds to the signal sequence and guides it and the attached protein to the . A key question for these researchers has been how the interaction between the signal sequence and SRP works in detail.

The Umeå scientists have managed to create a detailed picture of the first step in this protein transport by studying a complex of a signal sequence that is bound to the SRP. The technology they used is called x-ray crystallography. The group has shown the basic structure of the SRP in several previous studies SRP. Thanks to these studies, they were now able to directly compare the SRP structure with and without the guiding signal sequence.

”The structural changes were considerably greater than what was previously predicted. They provide us with detailed explanations of what role SRPs play in protein transport. These structural specifications can also serve as a model of how SRPs function at various levels during protein transport," explains Elisabeth Sauer-Eriksson, professor at the Department of Chemistry.

Now these researchers are moving on to try to investigate the next transport mechanism. For instance, they want to answer questions about what prompts the bound signal sequence to let go of the SRP and how the signal sequence, and the it is attached to, can make its way through the membrane.

Explore further: New research shows how pathogenic E. coli O157:H7 binds to fresh vegetables

More information: "Structural basis of signal-sequence recognition by the signal recognition particle," Tobias Hainzl, et al. Nature Structural and Molecular Biology.

add to favorites email to friend print save as pdf

Related Stories

How cells export and embed proteins in the membrane

Dec 13, 2010

Like an overprotective parent on the first day of school, a targeting factor sometimes needs a little push to let go of its cargo. Scientists at the European Molecular Biology Laboratory (EMBL) in Grenoble, ...

Scientists unveil mechanism for 'up and down' in plants

Oct 28, 2008

VIB researchers at Ghent University, Belgium, discovered how the transport of an important plant hormone is organized in a way that the plant knows in which direction its roots and leaves have to grow. They discovered how ...

A tricky tumor virus

Jan 17, 2008

Epstein-Barr virus (EBV) is a human-pathogenic virus which belongs to the herpes virus family. Almost every adult carries EBV inside. With an infestation rate of more than 90 %, EBV is one of the most successful human viruses. ...

Recommended for you

Lifestyle determines gut microbes

17 hours ago

An international team of researchers has for the first time deciphered the intestinal bacteria of present-day hunter-gatherers.

Rethink education to fuel bioeconomy, says report

19 hours ago

Microbes can be highly efficient, versatile and sophisticated manufacturing tools, and have the potential to form the basis of a vibrant economic sector. In order to take full advantage of the opportunity microbial-based ...

User comments : 0

More news stories

ESO image: A study in scarlet

This new image from ESO's La Silla Observatory in Chile reveals a cloud of hydrogen called Gum 41. In the middle of this little-known nebula, brilliant hot young stars are giving off energetic radiation that ...

First direct observations of excitons in motion achieved

A quasiparticle called an exciton—responsible for the transfer of energy within devices such as solar cells, LEDs, and semiconductor circuits—has been understood theoretically for decades. But exciton movement within ...

Patent talk: Google sharpens contact lens vision

(Phys.org) —A report from Patent Bolt brings us one step closer to what Google may have in mind in developing smart contact lenses. According to the discussion Google is interested in the concept of contact ...

Warm US West, cold East: A 4,000-year pattern

Last winter's curvy jet stream pattern brought mild temperatures to western North America and harsh cold to the East. A University of Utah-led study shows that pattern became more pronounced 4,000 years ago, ...