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: Two-armed control of ATR, a master regulator of the DNA damage checkpoint

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

Japanese scientist resigns over stem cell scandal

Dec 19, 2014

A researcher embroiled in a fabrication scandal that has rocked Japan's scientific establishment said Friday she would resign after failing to reproduce results of what was once billed as a ground-breaking study on ...

'Hairclip' protein mechanism explained

Dec 18, 2014

Research led by the Teichmann group on the Wellcome Genome Campus has identified a fundamental mechanism for controlling protein function. Published in the journal Science, the discovery has wide-ranging implications for bi ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.