View source for Cation-dependent Mannose-6-phosphate receptor

The mannose 6-phosphate receptor, also referred to as the cation-dependent mannose 6-phosphate receptor or CD-MPR, is one of two transmembrane proteins that bind mannose-6-phosphate (M6P) on lysosomal proteins in the Golgi apparatus that are destined for transport to the lysosome<ref>Sahagian, G. G. and Neufeld, E. F. Biosynthesis and turnover of the mannose 6-phosphate receptor in cultured Chinese hamster ovary cells. J Biol Chem 258, 7121-7128 (1983)</ref><ref>Hoflack, B. and Kornfeld, S. Purification and characterization of a cation-dependent mannose 6-phosphate receptor from murine P388D1 macrophages and bovine liver. J Biol Chem 260, 12008-12014 (1985)</ref><ref>Dahms, N. M. and Kornfeld, S. The cation-dependent mannose 6-phosphate receptor. Structural requirements for mannose 6-phosphate binding and oligomerization. J Biol Chem 264, 11458-11467 (1989)</ref><ref>Nair, P., Schaub, B. E. and Rohrer, J. Characterization of the endosomal sorting signal of the cation-dependent mannose 6-phosphate receptor. J Biol Chem 278, 24753-24758 (2003)</ref><ref>Sun, G., Zhao, H., Kalyanaraman, B. and Dahms, N. M. Identification of residues essential for carbohydrate recognition and cation dependence of the 46-kDa mannose 6-phosphate receptor. Glycobiology 15, 1136-1149 (2005)</ref><ref name="Kim 2009">Kim, J. J., Olson, L. J. and Dahms, N. M. Carbohydrate recognition by the mannose-6-phosphate receptors. Curr Opin Struct Biol 19, 534-542 (2009)</ref><ref name="Olson 2010">Olson, L. J., Sun, G., Bohnsack, R. N., Peterson, F. C., Dahms, N. M. and Kim, J. J. Intermonomer interactions are essential for lysosomal enzyme binding by the cation-dependent mannose 6-phosphate receptor. Biochemistry 49, 236-246 (2010)</ref>. The other protein is termed the cation-independent mannose-6-phosphate receptor or (CI-MPR) and is also the receptor for Insulin-like growth factor II<ref>Tong, P. Y., Tollefsen, S. E. and Kornfeld, S. The cation-independent mannose 6-phosphate receptor binds insulin-like growth factor II. J Biol Chem 263, 2585-2588 (1988)</ref><ref>Lobel, P., Dahms, N. M. and Kornfeld, S. Cloning and sequence analysis of the cation-independent mannose 6-phosphate receptor. J Biol Chem 263, 2563-2570 (1988)</ref><ref>Tong, P. Y. and Kornfeld, S. Ligand interactions of the cation-dependent mannose 6-phosphate receptor. Comparison with the cation-independent mannose 6-phosphate receptor. J Biol Chem 264, 7970-7975 (1989) </ref><ref>Hancock, M. K., Yammani, R. D. and Dahms, N. M. Localization of the carbohydrate recognition sites of the insulin-like growth factor II/mannose 6-phosphate receptor to domains 3 and 9 of the extracytoplasmic region. J Biol Chem 277, 47205-47212 (2002)</ref><ref>Bohnsack, R. N., Song, X., Olson, L. J., Kudo, M., Gotschall, R. R., Canfield, W. M., Cummings, R. D., Smith, D. F. and Dahms, N. M. Cation-independent mannose 6-phosphate receptor: a composite of distinct phosphomannosyl binding sites. J Biol Chem 284, 35215-35226 (2009)</ref><ref>Brown, J., Jones, E. Y. and Forbes, B. E. Keeping IGF-II under control: lessons from the IGF-II-IGF2R crystal structure. Trends Biochem Sci 34, 612-619 (2009)</ref><ref>Laube, F. Mannose-6-phosphate/insulin-like growth factor-II receptor in human melanoma cells: effect of ligands and antibodies on the receptor expression. Anticancer Res 29, 1383-1388 (2009)</ref>.

== CFG Participating Investigators contributing to the understanding of this paradigm ==
* CFG Participating Investigators (PIs) with interest in CD-MPR include: Ajit Varki
* Non-PIs using CFG resources to study the CD-MPR include: Nancy Dahms

== Progress toward understanding this GBP paradigm ==
This section documents what is currently known about the cation-dependent mannose-6-phosphate receptor, its carbohydrate ligand(s), and how they interact to mediate cell communication.
=== Carbohydrate ligands ===
The preferred ligands for the cation-dependent mannose 6-phosphate receptor are N-linked glycans that bear two terminal mannose 6-phosphate residues.<ref name=”Song2009”>Song, X, Lasanajak, Y, Olson, LJ, Boonen, M, Dahms, NM, Kornfeld, S, Cummings, RD and Smith, DF (2009) Glycan microarray analysis of P-type lectins reveals distinct phospho-mannose glycan recognition  J. Biol. Chem. 284, 35201-35214</ref>
<br>

=== Cellular expression of GBP and ligands ===
The cation-dependent mannose 6-phosphate receptor is expressed in most cell types in mammals.
<br>

=== Biosynthesis of ligands ===
The signal for binding to the mannose 6-phosphate receptor is generated in several steps. GlcNAc phosphate is first added to the reducing end mannose in terminal Man&alpha;1-2Man disaccharides in N-linked glycans by N-acetylglucosaminephosphotransferase to generate phosphodiesters. Removal of the GlcNAc moieties by an N-acetylglucosaminidase, known as an uncapping enzymes, which generates phosphomonoesters, which are required for binding to the cation-dependent mannose 6-phosphate receptor. The mannose residues at the non-reducing termini can then be removed. There are typically two phosphomonoesters per N-linked glycan. <ref name”Dahms2008”>Dahms, NM, Olson, LJ and Kim, J-JP (2008) Strategies for carbohydrate recognition by the mannose 6-phosphate receptors. Glycobiology 18, 664–678</ref>
<br>

=== Structure ===
The cation-dependent mannose 6-phosphate receptor has a luminal domain consisting of a single carbohydrate-recognition domain, and forms dimers in which these two domains typically interact with two mannose 6-phosphate residues on a single glycan. The crystal structure of the carbohydrate-recognition domain shows that the sugar moiety of mannose 6-phosphate makes hydrogen bonds to the hydroxyl groups at positions 2, 3 and 4, the orientations of which identify the sugar as mannose.  The phosphate moiety makes hydrogen bonds with backbone atoms and interacts with a Mn<sup>2+</sup> cation in the binding site.<ref name=”Roberts1998”>Roberts, DL, Weix, DJ, Dahms, NM and Kim, J-JP (1998) Molecular Basis of Lysosomal Enzyme Recognition: Three-Dimensional Structure of the Cation-Dependent Mannose 6-Phosphate Receptor Cell 93, 639-648</ref>
<br>

=== Biological roles of GBP-ligand interaction ===
The CD-MPR is found in all eukaryotes and is known to play a highly conserved role in recognition and targeting of lysosomal enzymes. Both CD-MPRs and CI-MPRs are glycan-binding proteins that bind their M6P-tagged cargo in the lumen of the Golgi apparatus <ref name="Kim 2009"/>. Once bound to their cargo, the MPRs are recognized by the GGA family of clathrin adaptor proteins and accumulate in forming clathrin-coated vesicles. Upon arriving at the early endosome, the low pH environment of the endosome induces the MPRs release their cargo. The MPRs are recycled back to the Golgi, again by way of interaction with GGAs and vesicles. The cargo proteins are then trafficked to the lysosome via the late endosome in a process independent of the MPRs <ref name="Kim 2009"/>. Cargo molecules undergo extensive processing terminating in terminal mannose-6 phosphate on one or more arms of the oligosaccharide.
<br>

== CFG resources used in investigations ==
The best examples of CFG contributions to this paradigm are described below, with links to specific data sets. For a complete list of CFG data and resources relating to this paradigm, see the [http://www.functionalglycomics.org/glycomics/search/jsp/landing.jsp?query=Mannose-6-phosphate&maxresults=20 CFG database search results for Mannose-6-phosphate].

=== Glycan profiling ===

<br>
=== Glycogene microarray ===

<br>
=== Knockout mouse lines ===

<br>
=== Glycan array ===
In 2006, soluble forms of MPR were screened on the CFG glycan array (click [http://www.functionalglycomics.org/glycomics/HServlet?operation=view&sideMenu=no&psId=primscreen_852 here]), but results were inconclusive.

== Related GBPs ==
The cation-independent mannose 6-phosphate receptor has a single carbohydrate-recognition domain in the MRH family, while the cation-independent mannose 6-phosphate receptor has 15 such repeats, at least three of which bind mannose 6-phosphate.

== References ==
<references/>

== Acknowledgements ==
The CFG is grateful to the following PIs for their contributions to this wiki page: John Hanover