PEP group translocation

The group translocation is a form of active transport of a substance (usually a monosaccharide, Simple sugars such as glucose ) across a cell membrane, which consumes energy and the substance is chemically altered during transport process.

The substance is phosphorylated in the group translocation during the transport process. Since after the conversion, the product is chemically different from the substance within the cell outside the cell, a concentration gradient across the membrane and thus a balance is avoided by back diffusion. The chemical modification of the " transport material " is the point that distinguishes the group translocation from other forms of active transportation. Group translocation has only been found in bacteria.

PEP -PTS in Escherichia coli

The best studied is the so-called Gruppentranslokationssystem phosphotransferase system (PTS ) of Escherichia coli, which was founded in 1964 discovered and investigated by Saul Roseman. In contrast to the usual ATP supplies here phosphoenolpyruvate ( PEP ) which is necessary for the active transport energy. Agent group translocation are also glucosamine N- acetylglucosamine, which is the basic building block of chitin and peptidoglycan, introduced in addition to glucose and mannose in the cell.

At the transport process by group translocation four different proteins are involved:

• Three -soluble proteins in the cytoplasm are located in front: the enzyme I ( EI ), the enzyme IIA (E II A) and the protein HPr
• A translocator (E IIB and IIC E ') " is fixed in the cell membrane.

Expiration of the translocation

Enzymes IIA, B, and C are each specific for the transported sugars. Thus, there are various enzymes required for all monosaccharides such as glucose, fructose and mannose. Enzyme I and HPr, however, are involved in each reaction, regardless of the type of sugar.