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==THE SOLUTION STRUCTURE OF THE B-FORM OF UROGUANYLIN-16 NMR, 10 STRUCTURES==
<StructureSection load='1uyb' size='340' side='right'caption='[[1uyb]]' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1uyb]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1UYB OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1UYB FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Solution NMR, 10 models</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=1uyb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1uyb OCA], [https://pdbe.org/1uyb PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1uyb RCSB], [https://www.ebi.ac.uk/pdbsum/1uyb PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1uyb ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/GUC2B_HUMAN GUC2B_HUMAN] Endogenous activator of intestinal guanylate cyclase. It stimulates this enzyme through the same receptor binding region as the heat-stable enterotoxins. May be a potent physiological regulator of intestinal fluid and electrolyte transport. May be an autocrine/paracrine regulator of intestinal salt and water transport.
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== Publication Abstract from PubMed ==
The peptide hormone uroguanylin stimulates chloride secretion via activation of intestinal guanylyl cyclase C (GC-C). It is characterized by two disulfide bonds in a 1-3/2-4 pattern that causes the existence of two topological stereoisomers of which only one induces intracellular cGMP elevation. To obtain an unambiguous structure-function relationship of the isomers, we determined the solution structure of the separated uroguanylin isoforms using NMR spectroscopy. Both isomers adopt well-defined structures that correspond to those of the isomers of the related peptide guanylin. Furthermore, the structure of the GC-C-activating uroguanylin isomer A closely resembles the structure of the agonistic Escherichia coli heat-stable enterotoxin. Compared with guanylin isomers, the conformational interconversion of uroguanylin isomers is retarded significantly. As judged from chromatography and NMR spectroscopy, both uroguanylin isoforms are stable at low temperatures, but are subject to a slow pH-dependent mutual isomerization at 37 degrees C with an equilibrium isomer ratio of approximately 1:1. The conformational exchange is most likely under the sterical control of the carboxy-terminal leucine. These results imply that GC-C is activated by ligands exhibiting the molecular framework corresponding to the structure of uroguanylin isomer A.

One peptide, two topologies: structure and interconversion dynamics of human uroguanylin isomers.,Marx UC, Klodt J, Meyer M, Gerlach H, Rosch P, Forssmann WG, Adermann K J Pept Res. 1998 Sep;52(3):229-40. PMID:9774236<ref>PMID:9774236</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
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</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Adermann K]]
[[Category: Forssmann W-G]]
[[Category: Marx UC]]
[[Category: Roesch P]]