For this purpose, certain membrane proteins act as ion channels, which transport the ions through the membrane. For example, signal transmission in a nerve cell is based on the fact that certain ions flow into or out of the cell at the right moment. Other proteins control the exchange of substances with the surroundings of the cell. Within seconds, this structural change also has an effect on the inner surface of the cell membrane and triggers certain chemical reactions within the cell, which lead to its transformation. The binding of VEGF to the receptor causes a change in the receptor structure. VEGF binds to the ends of a protein, a so-called receptor, which can be found on the outside of the cell.
A signal of this kind can be, for example, from a neurotransmitter molecule transmitting a signal from one nerve cell to the next, or a molecule (denoted by the abbreviation VEGF) which stimulates certain cells to develop into blood vessels. Hence there are a great number of proteins located in the membrane of a cell which pass signals from the exterior to the interior. All these processes are controlled by special proteins which can change their shape, and thereby their behaviour, depending on the external conditions. At the same time, the exchange of substances between the cell interior and its surroundings has to be managed. Thus, signals reach the cell from outside which trigger processes within the cell. As a result, they have been able to explain the mechanism which enables these proteins to recognise the filament ends and bind themselves to them.Īs part of a living organism, a living cell is in constant dialogue with its surroundings. Therefore, the scientists are engaged in a study of the proteins which connect the ends of cytoskeleton filaments with various different cell components, such as chromosomes or the cell membrane. Researchers at PSI are studying the structure of proteins involved in the cytoskeleton in order to understand the relationship between structure and function. During cell division, they separate the chromosomes destined for both newly forming cells, or participate in transporting cellular material to its destination within the cells. As needed, its filaments enable a cell to change its specific shape and to move. However, they do not form a stiff framework, but react flexibly to external influences and the specific needs of the cell, and are actively involved in numerous vital processes in the cell. Three types of polymer filaments are present in living cells that jointly make up the cytoskeleton, which stabilises cells and maintains their shape. This understanding could contribute to the targeted blocking of such processes in cancerous cells and to the slowing down of their further growth, or to causing their destruction. Many of the results achieved could contribute to the development of new cancer treatments in the long term, since research at PSI helps towards a better understand of the vital processes in biological cells.
Apart from their own research on protein structures, researchers are also involved in the development of new techniques for determining protein structures – in particular with synchrotron light at the Swiss Light Source (SLS) – and for the automated production of the large quantities of proteins required. Research topics include the study of proteins, which, as components of the cytoskeleton of a cell, give the cell its shape and enable its movements the study of membrane proteins that determine which substances must be transported into or out of a cell and how signals are transferred into a cell. Researchers at the Paul Scherrer Institute are studying several classes of proteins with the aim of understanding their structure and function.
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