Peptide membrane-associated

The VACM-1 receptor is a membrane-associated protein with a single putative transmembrane domain that binds selectively AVP (XD — 2 nM), but cannot discriminate between VXR and V2R analogues. It is expressed in endothelial and medullary collecting duct cells and upon stimulation by AVP. It induces a mobilization of cytosolic-free Ca2+, decreases cAMP production and inhibits cellular growth via MAPK phosphorylation and p53 expression. The mechanism of action and physiological functions of this new receptor are not well understood, but it seems to participate in the regulation of AVP induced signal transduction pathways or of a yet unidentified peptide. 

Naito A (2009) Structure elucidation of membrane-associated peptides and proteins in oriented bilayers by solid-state NMR spectroscopy. Solid State Nucl Mag 36 67-76... 

Aisenbrey C, Bertani P, Bechinger B (2010) Solid-state NMR investigations of membrane-associated antimicrobial peptides. Methods Mol Biol 618 209-233... 

Afonin S, Glaser RW, Berditchevskaia M, Wadhwani P, Guhrs KH, Mollmann U, Pemer A, Ulrich AS (2003) 4-Fluorophenylglycine as a label for F-19 NMR structure analysis of membrane-associated peptides. ChemBioChem 4 1151-1163... 

Wang G (2008) NMR of membrane-associated peptides and proteins. Curr Protein Pept Sci 9 50-69... 

A first approach to study the interaction of posttranslational modified Ras proteins with membranes was the analysis of binding and exchange of isoprenyl-ated peptides with and between lipid vesicles utilizing a fluorescent bimanyl label. Studies with K-Ras peptides revealed that a single isoprenyl group is sufficient for membrane association only if supported by carboxymethylation of the C-terminal cysteine [227,228]. 

Membrane-associated receptors are linked to transducing proteins (like G-proteins) in the inner portion of the membrane. G-protein coupled receptor (GPCR) families comprise a major class of the receptors that are pharmacologically relevant, such as muscarinic acetyl choline receptors, adrenoceptors, dopamine receptors, serotonine, opiate, peptide hormone, purinerg receptors, and also sensory chemoreceptors. A large variety of subtypes are described in the pharmacological literature. 

The results summarized above were obtained by using fluorescence based assays employing phospholipid vesicles and fluorescent labeled lipopeptides. Recently, surface plasmon resonance (SPR) was developed as new a technique for the study of membrane association of lipidated peptides. Thus, artificial membranes on the surface of biosensors offered new tools for the study of lipopeptides. In SPR (surface plasmon resonance) systemsI713bl changes of the refractive index (RI) in the proximity of the sensor layer are monitored. In a commercial BIAcore system1341 the resonance signal is proportional to the mass of macromolecules bound to the membrane and allows analysis with a time resolution of seconds. Vesicles of defined size distribution were prepared from mixtures of lipids and biotinylated lipopeptides by extruder technique and fused with a alkane thiol surface of a hydrophobic SPR sensor. 

Fig. 5.1 Schematic drawing of membrane association modes of peptides A Integral membrane proteins (1) major fd coat protein gpVIII of bacteriophage Ml 3 (pdb lfdm), anchored by an 18-residue trans-membrane hydrophobic helix (2) bovine rhodopsin, a 7 trans-membrane domain (G-protein-coupled) receptor (pdb lf88) (3) ion channel peptaibol Chrysospermin C (pdb lee7), and B Peripheral membrane proteins (1) neuro-...

The Structure and Dynamics of Membrane-Associated Peptides - A Case Study of Neuropeptide Y (NPY)... 

The structural analysis of membrane-associated peptides comprises two steps (a) the elucidation of the three-dimensional fold of the peptide and (b) the determination of the membrane-peptide interface. We will use our results gained for the 36 amino acid residue neuropeptide Y (NPY) [83] to demonstrate the approaches that can be used. NPY regulates important pharmacological functions such as blood pressure, food intake or memory retention and hence has been subject of many investigations (for a review see Ref. [84]). It targets the so-called Y receptors that belong to the class of seven transmembrane receptors coupled to G-proteins (GPCRs). 

NMR of Membrane-Associated Peptides and Proteins 5.3.3.2 Amide H,D Exchange... 

The generally low sensitivity of solid state NMR is significantly enhanced by using selective F-labels to analyze the structures of membrane-associated peptides and proteins [13,16-24]. This opens up a previously inaccessible range of experimental conditions, such as peptideiHpid ratios as low as 1 3000 [2 5 ]. This is particularly relevant for antibiotic peptides, as their concentration dependence constitutes an essential functional aspect [26]. A suitable side chain for labelling is 4F-phenylglycine (4F-Phg), as the F-reporter is fixed... 

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