Mannose 6-phosphate receptor homology (MRH) domain-containing lectins in the secretory pathway.

ABSTRACT: The mannose 6-phosphate receptor homology (MRH) domain-containing family of proteins, which include recycling receptors (mannose 6-phosphate receptors, MPRs), resident endoplasmic reticulum (ER) proteins (glucosidase II ?-subunit, XTP3-B, OS-9), and a Golgi glycosyltransferase (GlcNAc-phosphotransferase ?-subunit), are characterized by the presence of one or more MRH domains. Many MRH domains act as lectins and bind specific phosphorylated (MPRs) or non-phosphorylated (glucosidase II ?-subunit, XTP3-B and OS-9) high mannose-type N-glycans. The MPRs are the only proteins known to bind mannose 6-phosphate (Man-6-P) residues via their MRH domains.Recent biochemical and structural studies that have provided valuable insight into the glycan specificity and mechanisms of carbohydrate recognition by this diverse group of MRH domain-containing proteins are highlighted.Currently, three-dimensional structures are known for ten MRH domains, revealing the conservation of a similar fold. OS-9 and the MPRs use the same four residues (Gln, Arg, Glu, and Tyr) to bind mannose.The MRH domain-containing proteins play key roles in the secretory pathway: glucosidase II, XTP3-B, and OS-9 are involved in the recognition of nascent glycoproteins, whereas the MPRs play an essential role in lysosome biogenesis by targeting Man-6-P-containing lysosomal enzymes to the lysosome.

SUBMITTER: Castonguay AC 

PROVIDER: S-EPMC3150748 | biostudies-literature | 2011 Sep

REPOSITORIES: biostudies-literature