Mannose 6-phosphate

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Mannose 6-phosphate
CAS number 3672-15-9 YesY
PubChem 65127
ChemSpider 58636 Unspecified anomers YesY, 394282 alpha anomer YesY, 388338 beta anomer YesY
MeSH mannose-6-phosphate
ChEBI CHEBI:48066 YesY
Jmol-3D images Image 1
Image 3
Molecular formula C6H13O9P
Molar mass 260.136 g/mol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

Mannose-6-phosphate (M6P) is a molecule bound by lectin in the immune system. M6P is converted to fructose 6-phosphate by mannose phosphate isomerase.

M6P is a key targeting signal for acid hydrolase precursor proteins that are destined for transport to lysosomes. The M6P tag is added to such proteins in the cis-Golgi apparatus. Specifically, in a reaction involving uridine diphosphate (UDP) and N-acetylglucosamine, the enzyme N-acetylglucosamine-1-phosphate transferase catalyzes the N-linked glycosylation of asparagine residues with M6P. Once appropriately marked with the M6P targeting signal, these proteins are moved to the trans-Golgi network. There, the M6P moiety is recognized and bound by mannose 6-phosphate receptor (MPR) proteins at pH 6.5-6.7.[1]

The M6P-tagged lysosomal enzymes are shipped to the late endosomes via vesicular transport.[1] The pH in the late endosome can reach 6.0, which causes dissociation of M6P from its receptor.[1] Upon release, the enzymes are ferried to their final destination in the lysosomes.[1] The MPRs are packed into vesicles that bud off the late endosome and return to the "trans"-Golgi network.[1] In this way, the MPRs can be recycled.

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  1. ^ a b c d e Alberts, Bruce et al. (2002). Molecular biology of the cell (4th ed. ed.). New York: Garland Science. ISBN 0-8153-3218-1.