Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20366 (substance P)
 21,176 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We synthesized a novel ligand [4,5-3H-Leu9]-Neurokinin A (3H-NKA, S.A 117-144 Ci/mmol), and evaluated its binding to hamster urinary bladder membranes (HUBM). The ligand bound to HUBM in a highly-specific (94 +/- 4%) and protein-dependent manner. Binding was rapid (k1 = 0.037 nM-1*min-1) and saturable (Bmax = 1210 +/- 177 fmol/mg protein), to a single population of high-affinity sites (KD = 2.41 +/- 0.15 nM, nH = 0.99 +/- 0.02). Binding was inhibited by non-hydrolyzable GTP analogs. Competition experiments with HUBM demonstrated the following rank order of potency: NKA > Kassinin > [beta-Ala8]-NKA(4-10) > [Nle10]-NKA(4-10) = Eledoisin = NKB > Physaelamin > Substance P. The selective NK-1 and NK-3 ligands, [Sar9-Met (O2)11]-SP, (+/-) CP96,345 and Senktide respectively, did not inhibit binding at 10 microM, whereas, the selective NK-2 antagonists: (+/-) SR-48,968 >> L-659,877 > R396 >> MEN-10,207 > MEN-10,376, inhibited binding in a competitive manner. In contrast, the low specific binding (< 30%) detected in guinea pig lung membranes, was not inhibited by selective NK-2 ligands. Over 30 ligands (0.1-10 microM) from other receptor classes, were not inhibitory. The data suggest that this new ligand binds with high-affinity and selectivity to homogeneous population of NK-2 receptors on HUBM but not on lung membranes, and is a suitable ligand to study NK-2 receptors.
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PMID:Pharmacologic characterization of the novel ligand [4,5-3H-Leu9]neurokinin-A binding to NK-2 receptors on hamster urinary bladder membranes. 133 74

UC11 cells, derived from a human astrocytoma, have a high density of functional substance P receptors. Radioligand binding studies were conducted with the highly selective neurokinin-1 receptor ligand [3H][Sar9,Met(O2)11]-substance P. Kinetic binding experiments conducted at 4 degrees C yielded an association rate constant k1 of 1.86 x 10(7) M-1 min-1, a dissociation rate constant k-1 of 0.00478 min-1, and a calculated kinetic KD of 257 pM. Saturation binding experiments yielded average values of KD = 447 +/- 103 pM, Bmax = 862 +/- 93 fmol/mg of protein. This Bmax corresponds to more than 150,000 binding sites/cell. Competition binding experiments with unlabeled [Sar9,Met(O2)11]-substance P yielded average values of KD = 491 +/- 48 pM and Bmax = 912 +/- 67 fmol/mg of protein. In [3H]inositol-labeled cells, substance P induced a robust inositol phosphate formation. Inositol trisphosphate levels increased as much as 20-fold within approximately 15 s of addition of substance P. This inositol trisphosphate formation was transient and had returned to baseline within the first 60-120 s. Inositol monophosphate formation, however, was linear for at least 2 h. Structure activity data on binding and inositol monophosphate formation confirmed the presence of a neurokinin-1 receptor subtype in these cells. Thus, the UC11 cell should be a useful model cell for delineating the physiological role of substance P receptors in astrocytes.
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PMID:Characterization of receptors for substance P in human astrocytoma cells: radioligand binding and inositol phosphate formation. 137 Mar 19

In homogenates of guinea pig lung, binding of 125I-Bolton-Hunter-labeled substance P (BHSP), Bolton-Hunter-labeled eledoisin (BHELE), and [125I]iodohistidyl neurokinin A (INKA) was investigated. Equilibrium dissociation constants (derived from "cold" saturation experiments) for BHSP, INKA, and BHELE were 0.96 +/- 0.15, 1.61 +/- 0.26, and 1.98 +/- 0.12 nM, respectively. Specific binding of all three radioligands was increased 2-3-fold by 10 microM phosphoramidon. The rank order of potency of unlabeled tachykinins in competing against BHSP was substance P (SP) greater than [Sar9,Met(O2)11]-SP greater than SP methyl ester greater than neuropeptide gamma greater than neurokinin A greater than or equal to neurokinin B = kassinin greater than or equal to eledoisin greater than or equal to scyliorhinin II much greater than neuropeptide K, indicating binding to sites with the general characteristics of NK1 receptors. Similar rank potency orders were observed for INKA and BHELE, showing binding to NK1 sites, rather than to NK2 or NK3 sites, which are labeled with high affinity by these radioligands in other tissues. For all radioligands, competition curves for SP and the NK1-selective agonist [Sar9,Met(O2)11]-SP could be resolved into two components, representing high and low affinity binding sites. These were present in the approximate ratios 2:3 (for BHSP), 1:1 (for INKA), and 8:1 (for BHELE). Other agonist competition curves also yielded high and low affinity components. The data suggest that BHSP and INKA bind partly and BHELE predominantly to high affinity NK1 receptors. The nature of the low affinity site(s) could be another tachykinin receptor or a low affinity state of the NK1 receptor. Binding to a "classical" NK2 receptor is unlikely, because selective NK2 receptor antagonists and analogs were very weak competitors. Our data suggest that, in addition to the NK1 receptor, another type of tachykinin receptor may exist in this tissue. The inability to detect NK2 binding sites is strikingly at variance with functional studies.
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PMID:Radioiodinated substance P, neurokinin A, and eledoisin bind predominantly in NK1 receptors in guinea pig lung. 137 Jul 5

Tachykinins, a family of biologically active related peptides, are found in variable amounts in the rat hypothalamus. We assessed the effects of five tachykinins, substance P (SP), neurokinin A (NKA), neuropeptide K (NPK), neuropeptide gamma (NP gamma), and neurokinin B (NKB), on LH release in different experimental model systems in ovariectomized rats. In the first series of experiments rats were ovariectomized and implanted with permanent cannulae in the third cerebroventricle of the rat brain. Two weeks later, the effects of intracerebroventricular injection of 0.5 or 1.25 nm various tachykinins on LH release were studied. The results showed that whereas SP, NKA, and NKB were ineffective, and NP gamma was marginally effective, NPK produced a long-lasting suppression of LH release. NPK decreased LH release in a dose- and time-related fashion. Similarly, in the second series of experiments, whereas SP and NKA were inactive, NPK completely suppressed the LH surge induced by progesterone in estrogen-primed ovariectomized rats. In the third series of experiments we observed that NK-2 receptor agonist [Nle10]NKA4-10, and not NK-1 receptor agonist [Sar9,Met(O2)11]SP, suppressed both the release of LH in vivo and basal and KCl-induced hypothalamic LHRH release in vitro. These results show that NPK is the most effective tachykinin in suppressing LH release, and the inhibitory response is mediated by hypothalamic NK-2 receptors. These findings are in accord with the hypothesis that NPK may serve as a hypothalamic inhibitory neurotransmitter/neuromodulator of LHRH secretion.
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PMID:Effects of tachykinins on luteinizing hormone release in female rats: potent inhibitory action of neuropeptide K. 137 55

The molecular characteristics of the neuropeptide substance P (SP), its agonist [Sar9,Met-(O2)11]SP, and three of its antagonists [D-Arg1,D-Pro2,D-Trp7,9,Leu11]SP, [D-Arg1,D-Trp7,9,Leu11]SP, and [D-Pro2,D-Trp7,9]SP were investigated at the air/water interface and when bound to lipid monolayers and bilayers. Measurement of the Gibbs adsorption isotherm showed that the surface areas of SP and its agonist (240 +/- 5 A2 at biologically relevant concentrations) were distinctly larger than those of the antagonists (138 +/- 5 A2) [Seelig, A. (1990) Biochim. Biophys. Acta 1030, 111-118]. The surface activity of the peptides increased in the order [Sar9,Met(O2)11]SP less than SP less than [D-Pro2,D-Trp7,9]SP less than [D-Arg1,D-Trp7,9,Leu11]SP = [D-Arg1,D- Pro2,D-Trp7,9,Leu11]SP and correlated with the respective binding affinities to lipid membranes. The agonist did not insert into neutral and negatively charged bilayers or into densely packed lipid monolayers (at surface pressures greater than 31 mN/m). In contrast, the three antagonists gave rise to a strong binding both to neutral and to charged lipid monolayers and bilayers. The degree of binding was evaluated from the area increase of lipid monolayers upon peptide insertion, and the binding isotherms were analyzed in terms of the Gouy-Chapman theory. At the monolayer-bilayer equivalence pressure of approximately 32 mN/m, the binding can be described by a surface partition equilibrium with binding constants of (4.5 +/- 0.1) x 10(3) M-1 for [D-Pro2,D-Trp7,9]SP and (1.3 +/- 0.1) x 10(4) M-1 for both [D-Arg1,D-Trp7,9,Leu11]SP and [D-Arg1,D-Pro2,D-Trp7,9,Leu11]SP for pure palmitoyloleoylphosphatidylcholine (POPC) membranes.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Interaction of a substance P agonist and of substance P antagonists with lipid membranes. A thermodynamic analysis. 137 15

Binding of [3H]substance P (SP) and histamine release were examined using a cloned mouse mast cell line. SP binding was saturable and specific. In the presence of 30 mM Na2SO4/50 mM Tris buffer, SP interacted with two types of binding sites with Kd values of 0.3 and 40 nM. High-affinity SP binding was blocked by the inclusion of 0.5 uM of the NK1 receptor selective ligand septide in the binding mixture. Neurokinin A (NKA) evoked concentration-dependent histamine release. At concentrations in the nanomolar range, the NK1 preferring agonists SP, SP methylester and physalaemin evoked less than or equal to 5% net release of histamine, which was substantially less than the maximum effect of NKA (+37%) in the micromolar range. Pretreatment of the cells with the NK2 antagonist peptide A reduced NKA-induced histamine release. [D-Arg1,D-Phe5,D-Trp7,9,Leu11]-substance P, a putative SP antagonist, also elicited histamine release in the micromolar range, apparently acting as an agonist at the NK2 site. Compound 48/80, N-terminal SP fragments, neurokinin B and the two selective NK2 receptor antagonists cyclo(Gln-Trp-Phe-(R)-[ANC-2]Leu-Met) (peptide A) and cyclo(Gln-Trp-Phe-Gly-Leu-Met) (peptide B) were ineffective. Although the results suggest the coexistence of functional NK1 and NK2 receptors, it appears that in this mast cell line neurokinin-induced histamine release is primarily mediated by the NK2 receptor, characterized biochemically as a low affinity binding site with a Kd value of 40 nM for SP.
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PMID:Evidence of NK1 and NK2 tachykinin receptors and their involvement in histamine release in a murine mast cell line. 137 67

This study describes the synthesis and effects of the first antagonist to the widely distributed neuropeptide, galanin, which inhibits the secretion of insulin. The first galanin antagonist is a 20-amino acid-long chimeric peptide of the composition galanin-(1-12)-Pro-substance P-(5-11) amide: Gly-Trp-Thr-Leu-Asn-Ser-Ala-Gly-Tyr-Leu-Leu-Gly-Pro-Gln-Gln-Phe-Phe-Gly- Leu-Met amide. The peptide dose dependently (IC50 = 1.0 nM) antagonizes the galanin-mediated inhibition of the glucose-induced insulin secretion from mouse pancreatic islets. The antagonist was also found to displace 125I-monoiodo-[Tyr26]galanin from membranes of the insulin producing Rin m 5F cells with an IC50 value of less than 0.1 nM. The antagonist is named galantide.
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PMID:The novel high-affinity antagonist, galantide, blocks the galanin-mediated inhibition of glucose-induced insulin secretion. 137 72

Neutral endopeptidase 24.11 contains an active site arginine believed to function in substrate binding. This arginine is thought to form an ionic interaction with the COOH-terminal carboxylate of NEP substrates. The functionality of arginine 102 has been investigated by using site-directed mutagenesis to produce mutants in which this residue was converted to a lysine, glycine, glutamine, or glutamate. All of the mutants exhibited essentially full activity as determined with a synthetic peptide amide, glutaryl-Ala-Ala-Phe-4-methoxy-2-naphthylamide. In contrast, activity was detected only with the wild-type enzyme and the lysine mutant using a synthetic substrate containing a free COOH-terminal carboxylate, dansyl-Gly-Trp-Gly. Inhibition studies with the physiologically active peptide substrates substance P, endothelin, and angiotensin I, as well as substance P free acid, [D-Ala2,Leu5]enkephalin, and [D-Ala2,Leu5]enkephalinamide indicated a lack of importance of arginine 102 in substrate binding. With [D-Ala2,Met5]enkephalin and the chemotactic peptide, N-formyl-Met-Leu-Phe, a significant decrease in affinity is observed with the arginine 102 mutants. These results suggest that the contribution of arginine 102 to substrate binding is dependent upon the strength of other subsite interactions. Examination of dipeptides as inhibitors indicates that the nature and orientation of the P'2 residue is important in determining the strength of the interaction of arginine 102 with its substrates.
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PMID:Analysis of the importance of arginine 102 in neutral endopeptidase (enkephalinase) catalysis. 137 21

Neurokinin (NK) peptides such as substance P (SP) may modulate epithelial ion transport in the small intestine. The present study was undertaken to examine the pharmacological mechanisms by which SP and its endogenous homologs NKA and NKB affect active electrolyte transport in the mucosa of porcine jejunum. Neurokinins and NK agonist analogs increased short circuit current, a measure of active ion transport, across sheets of jejunal mucosa-submucosa with the order of potency: SP greater than [beta-Ala8]NKA4-10 greater than or equal to [Sar9,Met(O2)11]SP greater than NKA = Arg-NKB greater than NKB after their addition to the serosal aspect of tissues (SP EC50 = 11 nM). Epithelial responses to SP or NKA underwent rapid autotachyphylaxis and unidirectional cross-tachyphylaxis after repeated peptide administration. The neuronal conduction blocker tetrodotoxin significantly reduced NK efficacy. SP activity was significantly reduced in tissues pretreated with the muscarinic cholinoceptor blocker atropine or the eicosanoid synthesis inhibitor eicosa-5,8,11,14-tetraynoic acid. NK peptides increased contractility in longitudinally oriented strips of jejunal smooth muscle with an order of potency: [Sar9,Met(O2)11]SP greater than SP greater than Arg-NKB = [beta-Ala8]NKA4-10 greater than or equal to NKB = NKA (SP EC50 = 11 nM). SP-induced contractions were reduced by 70 to 80% in tissues pretreated with atropine or the neuronal Ca++ channel blocker, omega-conotoxin. [125I]Bolton-Hunter-substance P (BHSP) bound specifically to a single population of sites in slide-mounted sections of mucosa-submucosa and smooth muscle with Kd = 0.3 and 0.1 nM and Bmax = 18 and 31 fmol/mg protein, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Neurokinin receptors and mucosal ion transport in porcine jejunum. 137 58

A substance P (SP) analog, [D-Pro4,D-Trp7,9,10] SP4-11, is known to inhibit the actions of various structurally unrelated messenger molecules as well as SP. Our studies on the effects of this peptide on the regulation of purified G proteins by receptor showed that at least some of the biological effects of the peptide can be explained by the ability of the peptide to block the activation of G proteins by receptors. Here we report that a novel truncated SP-related peptide, pGlu-Gln-D-Trp-Phe-D-Trp-D-Trp-Met-NH2, inhibited the activation of G(i) or G(o) by M2 muscarinic cholinergic receptor (M2 mAChR) or of Gs by beta-adrenergic receptor in the reconstituted phospholipid vesicles, assayed by receptor-promoted GTP hydrolysis. The inhibition by the peptide was apparently reversible and competitive with respect to receptor binding to G proteins; the inhibition could be overcome by increasing the concentration of receptor in the vesicles and was not altered by changes in the concentration of G protein. The competing effects of the peptide were used to analyze the effect of agonist on receptor-G protein interaction. The concentration change of muscarinic agonist did not alter the inhibitory effects of the peptide on M2 mAChR-promoted GTPase by G(o), which is consistent with the idea that agonist increases the regulatory efficiency of the receptor but does not alter its affinity for G proteins. This new group of compounds (G protein antagonists) is a promising tool to study receptor-G protein interaction quantitatively.
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PMID:G protein antagonists. A novel hydrophobic peptide competes with receptor for G protein binding. 137 92


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