1tz5 | pdb_00001tz5
[pNPY19-23]-hPP bound to DPC Micelles
Structural highlights
Function[PAHO_HUMAN] Pancreatic hormone is synthesized in pancreatic islets of Langerhans and acts as a regulator of pancreatic and gastrointestinal functions. The physiological role for the icosapeptide has not yet been elucidated. 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 PubMedNeuropeptide Y (NPY) and the pancreatic polypeptide (PP) are members of the neuropeptide Y family of hormones. They bind to the Y receptors with very different affinities: Whereas PP is highly selective for the Y(4) receptor, NPY displays highest affinites for Y(1), Y(2), and Y(5) receptor subtypes. Introducing the NPY segment 19-23 into PP leads to an increase in affinity at the Y(1) and Y(2) receptor subtypes whereas the exchange of this segment from PP into NPY leads to a large decrease in affinity at all receptor subtypes. PP displays a very stable structure in solution, with the N terminus being back-folded onto the C-terminal alpha-helix (the so-called PP-fold). The helix of NPY is less stable and the N terminus is freely diffusing in solution. The exchange of this segment, however, does not alter the PP-fold propensities of the chimeric peptides in solution. The structures of the phospholipid micelle-bound peptides serving to mimic the membrane-bound species display segregation into a more flexible N-terminal region and a well-defined alpha-helical region. The introduction of the [19-23]-pNPY segment into hPP leads to an N-terminal extension of the alpha-helix, now starting at Pro(14) instead of Met(17). In contrast, a truncated helix is observed in [(19)(-)(23)hPP]-pNPY, starting at Leu(17) instead of Ala(14). All peptides display moderate binding affinities to neutral membranes (K(assoc) in the range of 1.7 to 6.8 x 10(4) mol(-)(1) as determined by surface plasmon resonance) with the differences in binding being most probably related to the exchange of Arg-19 (pNPY) by Glu-23 (hPP). Differences in receptor binding properties between the chimeras and their parental peptides are therefore most likely due to changes in the conformation of the micelle-bound peptides. Strongly altered receptor binding properties in PP and NPY chimeras are accompanied by changes in structure and membrane binding.,Lerch M, Kamimori H, Folkers G, Aguilar MI, Beck-Sickinger AG, Zerbe O Biochemistry. 2005 Jun 28;44(25):9255-64. PMID:15966750[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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