Discovered protein reveals the secret of the cell membrane


06/05/2010

A team of scientists from The Scripps Research Institute (The Scripps Research Institute) and the National Institutes of Health (National Institutes of Health) found the protein structure, which pinch off tiny pouches from the outer membrane of our cells. These cells are used for pouches or vesicle movement of nutrients and other essential substances.

The structure of the protein dynamin will help shed light on the formation of vesicles and advance in the understanding of the underlying processes that are critical for cell survival. The opening can also help to improve drug delivery methods.

An article about the study was published in the online version of the journal Nature, April 28, 2010.

Riddle nibbles membranes

The cell membrane acts as a barrier to protect the cell from penetrating into the harmful substances. But to sustain life, the cell, and also needs to get inside it some substance.

To get into the cell, nutrients or hormones in the bloodstream, for example attached to a specific receptor on the cell membrane. Then, the membrane forms around these molecules linked recess and they are pressed into a bag or a vial, which is detached from the membrane and carries its important cargo into the cell. Nerve cells employ a similar bubble-forming mechanism called endocytosis, in order to support the process of receiving signals to each other.

"Endocytosis - a way of communicating cells," - said Sandra Schmid, head of the department of molecular biology and the author of the article in the journal Nature, - "It is critically important for many biological processes, ranging from the control of blood pressure and ending with disposal of glucose."

Scientists have for a long time did not understand exactly how this process works. But it is certain that at least one molecule, called dynamin, played an important role in it.

Dynamin belongs to a large family of enzymes called GTPase. These enzymes bind GTP chemical and convert it into a simpler form (ODS), which releases energy. In the process of converting GTPase changes its shape, which allows it to perform the function for the production of vesicles.

Initially, scientists believed that the molecules dynamin going into long spirals on the cell membrane and in the presence of GTP these spirals harden, creating vesicles.

But the study, conducted a year ago, has cast doubt on that view. Watching the transformation of the vesicles through a microscope, the researchers found that the protein dynamin forms only a small ring around the membrane. Besides, dynamin may function alone, without the aid of other proteins.

How to determine the function of the protein? This can be done, for example, in his structure. To this end, scientists have employed a method called X-ray crystallography, which is created in the crystal form of the protein, which is bombarded with X-rays to determine the position of atoms.

But in the case of dynamin, the crystallization process was difficult, because this protein is composed of almost 1,000 amino acids. The solution was found about 3 years ago when Chappy Joshua (Joshua Chappie) managed to create a shorter version of dynamin, which retained the same GTPase activity to that of complete protein.

Chappy easily create a truncated protein crystal and examined it using X-ray crystallography. But the data was not possible to interpret because of

The resulting crystal structure of the shortened dynamin has opened a lot of important information.

"Thanks to this structure, yielded many answers to the questions we asked during the last decade," - said Schmid. Visit the news portal, argue, argue, prove.

Original: Sciencedaily.com


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