Mannose-6-phosphate

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Structural formula
D-mannose-6-phosphate
General
Surname Mannose-6-phosphate
Molecular formula C 6 H 13 O 9 P
External identifiers / databases
CAS number 3672-15-9 ( D- mannose-6-phosphate)
PubChem 65127
ChemSpider 58636
Wikidata Q259546
properties
Molar mass 260.14 g mol −1
Physical state

firmly

safety instructions
GHS hazard labeling
no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

D - Mannose-6-phosphate , abbreviation M6P , is a phosphoric acid ester of mannose . M6P is an important metabolite of many metabolic processes in all living things.

Physiological importance

Free Mannose is within a cell by hexokinase to M6P phosphorylated , whereby it can not leave the cell. If the cell does not need M6P for the production of glycoproteins , it can be converted into fructose-6-phosphate under the catalytic influence of the enzyme mannose-6-phosphate isomerase , which can be utilized by means of glycolysis .

Mannose-6-phosphate serves as a recognition molecule for lysosomal enzymes. The hydrolases produced in the rough endoplasmic reticulum carry oligosaccharides with several mannose residues bound to nitrogen. These mannose residues are phosphorylated in the cis Golgi network . The M6P residue formed is of great importance for the further transport of these enzymes. Signal areas in the peptide sequence ensure in the cell that only the mannose groups of the lysosomal enzymes and not those of other enzymes are phosphorylated. The phosphorylation takes place in two enzymatically catalyzed steps. The phosphotransferase N -acetylglucosaminyl-1-phosphotransferase (EC 2.7.8.17, GlcNAc-phosphotransferase) initially adds an N -acetylglucosamine -1-phosphate residue to an asparagine . A second enzyme, N -acetylglucosamine-1-phosphodiester-α- N -acetylglucosaminidase , then cuts off the N -acetylglucosamine residue. The number of M6P units correlates with the strength of the detection signal. Membrane-bound mannose-6-phosphate receptors of the trans-Golgi network bind provide to the M6P units of the enzymes and for the formation of clathrin -umhüllten vesicles ( clathrin coated vesicles which the complex formed from enzyme-M6P and M6P receptor) include. The vesicles first lose their clathrin shell before they fuse with the endolysosome . Due to the low pH value in the lysosome, the complex is destroyed again and the phosphate residue is split off from the mannose. The released M6P receptors are transported back into the trans-Golgi network via vesicles, where they are again available for enzyme transport.

further reading

Individual evidence

  1. This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
  2. F. Horn: Biochemistry of humans. Georg Thieme Verlag, 2009, ISBN 3-131-30884-2 , p. 121. Restricted preview in the Google book search
  3. G. Rehner, H. Daniel: Biochemistry of nutrition. Verlag Springer, 2010, ISBN 3-827-42041-5 , pp. 79-80. limited preview in Google Book search