Two-component system (cell biology)

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Two-component system ( two-component system , TCS) referred to in the cell biology quite general system of transmission of information of interest in a cell .

Living cells depend on external signals that indicate a change in the environment (e.g. a change in pressure or gradients of food molecules), being passed on to the inside of the cell. This process, called signal transduction , allows the cell to respond appropriately to the signal. In many cells a scheme is used for this in which, among other things, two protein components are involved, which always perform the same task. One speaks of a two-component system. Two-component systems are found in bacteria, archaebacteria, eukaryotic protozoa, fungi and higher plants, but not in mammalian cells.

In bacteria, most two-component systems consist of a transmembrane protein that acts as a sensor and a cytoplasmic protein that controls the regulation of a process. The sensor protein reacts to an external signal by attaching a phosphate group to a specific point on the protein. More precisely, a histidine is phosphorylated . The sensor protein is also a kinase , which is why it is also referred to as sensor kinase . In a second step, the phosphate group is transferred to the regulatory protein, which is activated as a result. The activated regulatory protein usually interferes with gene expression. Chemotaxis is an exception , in which the regulatory protein directly influences the swimming direction of the bacterium.

In higher cells, the process is more complicated because more components are involved. This allows the cells to respond more finely to an external stimulus.

Examples of two-component systems

literature

  • Georg Fuchs, Thomas Eitinger, Hans Günter Schlegel: General microbiology. Georg Thieme, 2007. ISBN 9783134446081 . P. 498.
  • Detlef Doenecke, Peter Karlson: Karlsons Biochemie and Pathobiochemie . Georg Thieme, 2005. ISBN 9783133578158 . P. 495.