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N-terminal 3 domains of CI-MPR bound to mannose 6-phosphate
Structural highlights
FunctionMPRI_BOVIN Acts as a positive regulator of T-cell coactivation, by binding DPP4 (By similarity). Transport of phosphorylated lysosomal enzymes from the Golgi complex and the cell surface to lysosomes. Lysosomal enzymes bearing phosphomannosyl residues bind specifically to mannose-6-phosphate receptors in the Golgi apparatus and the resulting receptor-ligand complex is transported to an acidic prelyosomal compartment where the low pH mediates the dissociation of the complex. This receptor also binds IGF2. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe 300-kDa cation-independent mannose 6-phosphate receptor (CI-MPR) plays a critical role in the trafficking of newly synthesized mannose 6-phosphate-containing acid hydrolases to the lysosome. The receptor contains two high affinity carbohydrate recognition sites within its 15-domain extracytoplasmic region, with essential residues for carbohydrate recognition located in domain 3 and domain 9. Previous studies have shown that these two sites are distinct with respect to carbohydrate specificity. In addition, expression of truncated forms of the CI-MPR demonstrated that domain 9 can be expressed as an isolated domain, retaining high affinity (Kd approximately 1 nm) carbohydrate binding, whereas expression of domain 3 alone resulted in a protein capable of only low affinity binding (Kd approximately 1 microm) toward a lysosomal enzyme. In the current report the crystal structure of the N-terminal 432 residues of the CI-MPR, encompassing domains 1-3, was solved in the presence of bound mannose 6-phosphate. The structure reveals the unique architecture of this carbohydrate binding pocket and provides insight into the ability of this site to recognize a variety of mannose-containing sugars. The N-terminal carbohydrate recognition site of the cation-independent mannose 6-phosphate receptor.,Olson LJ, Dahms NM, Kim JJ J Biol Chem. 2004 Aug 6;279(32):34000-9. Epub 2004 May 28. PMID:15169779[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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