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| | <StructureSection load='1g13' size='340' side='right'caption='[[1g13]], [[Resolution|resolution]] 2.00Å' scene=''> | | <StructureSection load='1g13' size='340' side='right'caption='[[1g13]], [[Resolution|resolution]] 2.00Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[1g13]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Human Human]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1G13 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1G13 FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[1g13]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1G13 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1G13 FirstGlance]. <br> |
| - | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=EPE:4-(2-HYDROXYETHYL)-1-PIPERAZINE+ETHANESULFONIC+ACID'>EPE</scene></td></tr> | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2Å</td></tr> |
| - | <tr id='NonStdRes'><td class="sblockLbl"><b>[[Non-Standard_Residue|NonStd Res:]]</b></td><td class="sblockDat"><scene name='pdbligand=MSE:SELENOMETHIONINE'>MSE</scene></td></tr> | + | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=EPE:4-(2-HYDROXYETHYL)-1-PIPERAZINE+ETHANESULFONIC+ACID'>EPE</scene>, <scene name='pdbligand=MSE:SELENOMETHIONINE'>MSE</scene></td></tr> |
| | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1g13 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1g13 OCA], [https://pdbe.org/1g13 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1g13 RCSB], [https://www.ebi.ac.uk/pdbsum/1g13 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1g13 ProSAT]</span></td></tr> | | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1g13 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1g13 OCA], [https://pdbe.org/1g13 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1g13 RCSB], [https://www.ebi.ac.uk/pdbsum/1g13 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1g13 ProSAT]</span></td></tr> |
| | </table> | | </table> |
| | == Disease == | | == Disease == |
| - | [[https://www.uniprot.org/uniprot/SAP3_HUMAN SAP3_HUMAN]] Defects in GM2A are the cause of GM2-gangliosidosis type AB (GM2GAB) [MIM:[https://omim.org/entry/272750 272750]]; also known as Tay-Sachs disease AB variant. GM2-gangliosidosis is an autosomal recessive lysosomal storage disease marked by the accumulation of GM2 gangliosides in the neuronal cells. GM2GAB is characterized by GM2 gangliosides accumulation in the presence of both hexosaminidase A and B.<ref>PMID:1915858</ref> <ref>PMID:8244332</ref> <ref>PMID:8900233</ref>
| + | [https://www.uniprot.org/uniprot/SAP3_HUMAN SAP3_HUMAN] Defects in GM2A are the cause of GM2-gangliosidosis type AB (GM2GAB) [MIM:[https://omim.org/entry/272750 272750]; also known as Tay-Sachs disease AB variant. GM2-gangliosidosis is an autosomal recessive lysosomal storage disease marked by the accumulation of GM2 gangliosides in the neuronal cells. GM2GAB is characterized by GM2 gangliosides accumulation in the presence of both hexosaminidase A and B.<ref>PMID:1915858</ref> <ref>PMID:8244332</ref> <ref>PMID:8900233</ref> |
| | == Function == | | == Function == |
| - | [[https://www.uniprot.org/uniprot/SAP3_HUMAN SAP3_HUMAN]] The large binding pocket can accommodate several single chain phospholipids and fatty acids, GM2A also exhibits some calcium-independent phospholipase activity (By similarity). Binds gangliosides and stimulates ganglioside GM2 degradation. It stimulates only the breakdown of ganglioside GM2 and glycolipid GA2 by beta-hexosaminidase A. It extracts single GM2 molecules from membranes and presents them in soluble form to beta-hexosaminidase A for cleavage of N-acetyl-D-galactosamine and conversion to GM3.
| + | [https://www.uniprot.org/uniprot/SAP3_HUMAN SAP3_HUMAN] The large binding pocket can accommodate several single chain phospholipids and fatty acids, GM2A also exhibits some calcium-independent phospholipase activity (By similarity). Binds gangliosides and stimulates ganglioside GM2 degradation. It stimulates only the breakdown of ganglioside GM2 and glycolipid GA2 by beta-hexosaminidase A. It extracts single GM2 molecules from membranes and presents them in soluble form to beta-hexosaminidase A for cleavage of N-acetyl-D-galactosamine and conversion to GM3. |
| | == Evolutionary Conservation == | | == Evolutionary Conservation == |
| | [[Image:Consurf_key_small.gif|200px|right]] | | [[Image:Consurf_key_small.gif|200px|right]] |
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| | <jmolCheckbox> | | <jmolCheckbox> |
| | <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/g1/1g13_consurf.spt"</scriptWhenChecked> | | <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/g1/1g13_consurf.spt"</scriptWhenChecked> |
| - | <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked> | + | <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.spt</scriptWhenUnchecked> |
| | <text>to colour the structure by Evolutionary Conservation</text> | | <text>to colour the structure by Evolutionary Conservation</text> |
| | </jmolCheckbox> | | </jmolCheckbox> |
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| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| - | [[Category: Human]] | + | [[Category: Homo sapiens]] |
| | [[Category: Large Structures]] | | [[Category: Large Structures]] |
| - | [[Category: Li, S C]] | + | [[Category: Li SC]] |
| - | [[Category: Rastinejad, F]] | + | [[Category: Rastinejad F]] |
| - | [[Category: Wright, C S]] | + | [[Category: Wright CS]] |
| - | [[Category: Beta cup]]
| + | |
| - | [[Category: Ligand binding protein]]
| + | |
| Structural highlights
Disease
SAP3_HUMAN Defects in GM2A are the cause of GM2-gangliosidosis type AB (GM2GAB) [MIM:272750; also known as Tay-Sachs disease AB variant. GM2-gangliosidosis is an autosomal recessive lysosomal storage disease marked by the accumulation of GM2 gangliosides in the neuronal cells. GM2GAB is characterized by GM2 gangliosides accumulation in the presence of both hexosaminidase A and B.[1] [2] [3]
Function
SAP3_HUMAN The large binding pocket can accommodate several single chain phospholipids and fatty acids, GM2A also exhibits some calcium-independent phospholipase activity (By similarity). Binds gangliosides and stimulates ganglioside GM2 degradation. It stimulates only the breakdown of ganglioside GM2 and glycolipid GA2 by beta-hexosaminidase A. It extracts single GM2 molecules from membranes and presents them in soluble form to beta-hexosaminidase A for cleavage of N-acetyl-D-galactosamine and conversion to GM3.
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 PubMed
GM2 activator protein (GM2-AP) belongs to a small group of non- enzymatic lysosomal proteins that act as cofactors in the sequential degradation of gangliosides. It has been postulated that GM2-AP extracts single GM2 molecules from membranes and presents them in soluble form to beta-hexosaminidase A for cleavage of N-acetyl-d-galactosamine and conversion to GM3. The high affinity of GM2-AP for GM2 is based on specfic recognition of the oligosaccharide moiety as well as the ceramide lipid tail. Genetic defects in GM2-AP result in an atypical form of Tay-Sachs disease known as variant AB GM2 gangliosidosis. The 2.0 A resolution crystal structure of GM2-AP reported here reveals a previously unobserved fold whose main feature is an eight-stranded cup-shaped anti-parallel beta-pleated sheet. The striking feature of the GM2-AP structure is that it possesses an accessible central hydrophobic cavity rather than a buried hydrophobic core. The dimensions of this cavity (12 Ax14 Ax22 A) are suitable for binding 18-carbon lipid acyl chains. Flexible surface loops and a short alpha-helix decorate the mouth of the beta-cup and may control lipid entry to the cavity.
Crystal structure of human GM2-activator protein with a novel beta-cup topology.,Wright CS, Li SC, Rastinejad F J Mol Biol. 2000 Dec 1;304(3):411-22. PMID:11090283[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Schroder M, Schnabel D, Suzuki K, Sandhoff K. A mutation in the gene of a glycolipid-binding protein (GM2 activator) that causes GM2-gangliosidosis variant AB. FEBS Lett. 1991 Sep 23;290(1-2):1-3. PMID:1915858
- ↑ Schroder M, Schnabel D, Hurwitz R, Young E, Suzuki K, Sandhoff K. Molecular genetics of GM2-gangliosidosis AB variant: a novel mutation and expression in BHK cells. Hum Genet. 1993 Nov;92(5):437-40. PMID:8244332
- ↑ Schepers U, Glombitza G, Lemm T, Hoffmann A, Chabas A, Ozand P, Sandhoff K. Molecular analysis of a GM2-activator deficiency in two patients with GM2-gangliosidosis AB variant. Am J Hum Genet. 1996 Nov;59(5):1048-56. PMID:8900233
- ↑ Wright CS, Li SC, Rastinejad F. Crystal structure of human GM2-activator protein with a novel beta-cup topology. J Mol Biol. 2000 Dec 1;304(3):411-22. PMID:11090283 doi:http://dx.doi.org/10.1006/jmbi.2000.4225
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