View source for 3top


==Crystral Structure of the C-terminal Subunit of Human Maltase-Glucoamylase in Complex with Acarbose==
<StructureSection load='3top' size='340' side='right'caption='[[3top]], [[Resolution|resolution]] 2.88&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[3top]] is a 2 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=3TOP OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3TOP FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.881&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=AC1:6-METHYL-5-(4,5,6-TRIHYDROXY-3-HYDROXYMETHYL-CYCLOHEX-2-ENYLAMINO)-TETRAHYDRO-PYRAN-2,3,4-TRIOL'>AC1</scene>, <scene name='pdbligand=GLC:ALPHA-D-GLUCOSE'>GLC</scene>, <scene name='pdbligand=PRD_900007:alpha-acarbose'>PRD_900007</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=3top FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3top OCA], [https://pdbe.org/3top PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3top RCSB], [https://www.ebi.ac.uk/pdbsum/3top PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3top ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/MGA_HUMAN MGA_HUMAN] May serve as an alternate pathway for starch digestion when luminal alpha-amylase activity is reduced because of immaturity or malnutrition. May play a unique role in the digestion of malted dietary oligosaccharides used in food manufacturing.
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== Publication Abstract from PubMed ==
Human maltase-glucoamylase (MGAM) hydrolyzes linear alpha-1,4-linked oligosaccharide substrates, playing a crucial role in the production of glucose in the human lumen and acting as an efficient drug target for type 2 diabetes and obesity. The amino- and carboxyl-terminal portions of MGAM (MGAM-N and MGAM-C) carry out the same catalytic reaction but have different substrate specificities. In this study, we report crystal structures of MGAM-C alone at a resolution of 3.1 A, and in complex with its inhibitor acarbose at a resolution of 2.9 A. Structural studies, combined with biochemical analysis, revealed that a segment of 21 amino acids in the active site of MGAM-C forms additional sugar subsites (+ 2 and + 3 subsites), accounting for the preference for longer substrates of MAGM-C compared with that of MGAM-N. Moreover, we discovered that a single mutation of Trp1251 to tyrosine in MGAM-C imparts a novel catalytic ability to digest branched alpha-1,6-linked oligosaccharides. These results provide important information for understanding the substrate specificity of alphaglucosidases during the process of terminal starch digestion, and for designing more efficient drugs to control type 2 diabetes or obesity.

Structural insight into substrate specificity of human intestinal maltase-glucoamylase.,Ren L, Qin X, Cao X, Wang L, Bai F, Bai G, Shen Y Protein Cell. 2011 Oct;2(10):827-36. Epub 2011 Nov 6. PMID:22058037<ref>PMID:22058037</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 3top" style="background-color:#fffaf0;"></div>

==See Also==
*[[Alpha-glucosidase 3D structures|Alpha-glucosidase 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Qin XH]]
[[Category: Ren LM]]
[[Category: Shen Y]]