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)

Three chimeric receptors were constructed by exchanging exons between human neurokinin NK1 and NK3 receptor genes. The N-terminal sequences of these chimeric receptors are encoded by exon 1, exon 1-2, or exon 1-3 of the NK1 receptor gene, whereas the remaining C-terminal sequences of these chimeric receptors are encoded by corresponding exons of the human NK3 receptor gene. Substance P bound with high affinities to all three chimeric receptors, suggesting that in addition to the common structures composed of conserved amino acid residues among neurokinin receptors, structural elements encoded by the first exon of the human NK1 receptor gene may also play an important role for substance P binding. On the contrary, potent NK1 antagonists L703,606 and SR140,333 did not show any detectable binding to these chimeric receptors. In accordance, sequences encoded by exon 4, and possibly exon 5, are likely to contain important structural motifs that may directly or indirectly influence the binding of these antagonists. Further comparison of the binding affinities of highly selective NK1 agonists, [Sar9, Met(O2)11] substance P, substance P methyl ester, and septide, revealed that each agonist may interact differently with the human NK1 receptor. These results show that the exon-exchanging technique can be a useful tool for studying structure-function relationships of receptors in which exon-intron junctions are fully conserved among receptor subtypes.
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PMID:Structural motifs encoded by individual exons of the human neurokinin-1 receptor gene interact differentially with selective agonists and antagonists. 875 26

Residues in transmembrane domain (TM)-III, TM-V, TM-VI, and TM-VII believed to be facing the deep part of the presumed main ligand-binding pocket of the NK1 receptor were probed by alanine substitution and introduction of residues with larger and/or chemically distinct side chains. Unaltered or even improved binding affinity for four peptide agonists, substance P, substance P-O-methyl ester, eledoisin, and neurokinin A, as well as normal EC50 values for substance P in stimulating phosphatidylinositol turnover indicated that these mutations did not alter the overall functional integrity of the receptor. The alanine substitutions in general had only minor effects on nonpeptide antagonist binding. However, the introduction of the larger and polar aspartic acid and histidine residues at positions corresponding to the monoamine binding aspartic acid in TM-III of the beta 2-adrenoceptor (ProIII:08, Pro112 in the NK1 receptor) and to the presumed monoamine interacting "two serines" in TM-V (ThrV:09, Thr201; and IleV:12, Ile204) impaired by > 100-fold the binding of a group of nonpeptide antagonists, including CP96,345, CP99,994, RP67,580, RPR100,893, and CAM4092. In contrast, another group of nonpeptide antagonists, LY303,870, FK888, and SR140,333, were little or not at all affected by the space-filling substitutions. Two of these compounds, FK888 and LY303,870, were those most seriously affected (75-89-fold) by alanine substitution of PheVI:20 located in the upper part of the main ligand-binding crevice. Surprisingly, substitution of AlaIII:11 (Ala115), which is located in the middle of TM-III, conceivably pointing toward TM-VII, with a larger valine residue increased the affinity for all 13 ligands tested, presumably by creating a closer interhelical packing. It is concluded that the introduction of larger side chains at positions at which molecular models indicate that this is structurally allowed can be a powerful method of locating ligand-binding sites due to the considerable difference between positive and negative results. Such steric hindrance mutagenesis strongly indicates that one population of nonpeptide antagonists bind in the deep pocket of the main ligand-binding crevice of the NK1 receptor, whereas another group of nonpeptide antagonists, especially SR140,333, was surprisingly resistant to mutational mapping in this pocket.
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PMID:Steric hindrance mutagenesis versus alanine scan in mapping of ligand binding sites in the tachykinin NK1 receptor. 944 45

1. The binding modalities of substance P and neurokinin A on the wild type and Gly166 to-Cys mutant NK1 receptors expressed on CHO cells were investigated in homologous and heterologous binding experiments using both radiolabelled substance P and neurokinin A. 2. On the wild type NK1 receptor NKA displaces radiolabelled substance P with very low apparent affinity, despite its high-affinity binding constant (determined in homologous binding experiments). The Gly166 to-Cys substitution in the NK1 tachykinin receptor greatly enhances the apparent affinity of neurokinin A in competition for radiolabelled substance P, but it does not change the binding constant of neurokinin A. The mutation, thereby, eliminates the discrepancy between the low apparent affinity and the high binding constant of neurokinin A. 3. On the wild type receptor the binding capacity of neurokinin A is significantly smaller than that of substance P. In contrast, the two tachykinins bind to approximately the same number of sites on the mutant receptor. 4. Simultaneous mass action law analysis of binding data in which multiple radioligands were employed in parallel demonstrated that a one-site model was unable to accommodate all the experimental data, whereas a two-site model provided a dramatically better description. 5. These two receptor-sites display equally high affinity for substance P, while neurokinin A strongly discriminates between a high and a low affinity component. The binding affinities of neurokinin A are not affected by the mutation, which instead specifically alters the distribution between receptor sites in favour of a high affinity neurokinin A binding form. 6. The low apparent affinity and binding capacity of neurokinin A on the wild type receptor results from neurokinin A binding with high affinity only to a fraction of the sites labelled by substance P. The mutation increases the proportion of this site, and consequently enhances the apparent affinity and binding capacity of neurokinin A. 7. The binding modalities of septide-like ligands (i.e. neurokinin B, SP(6-11), SP-methyl ester) are affected similarly to neurokinin A and are better resolved into two sites. The mutation leaves the affinity of these ligands for the two receptor forms unchanged, but increases the fraction of high-affinity sites. On the other hand, the binding of non-peptide and peptide antagonists (SR140.333 and FK888) behaved similarly to substance P with a single high affinity site that is unaffected by the mutation. 8. These findings may suggest that the NK1 receptor exists in two different forms with similar affinity for substance P and NK1 antagonists, but with a high and a low affinity for neurokinin A and septide-like ligands. Hence, the Gly166 in the NK1 receptor would seem to control the distribution between a pan-reactive form and a substance P-selective form of the receptor.
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PMID:Point mutation increases a form of the NK1 receptor with high affinity for neurokinin A and B and septide. 978 14

The effect of selective neurokinin receptor (NKR) antagonists for the NK1R (SR140,333), NK2R (SR48,968), and NK3R (SR142,801) on the visceromotor response to noxious colorectal distension (CRD) was examined. NKR antagonists or vehicle were given intrathecally (i.th.) to rats made hyperalgesic by intracolonic instillation of zymosan or after intracolonic instillation of saline (control). Given alone, the NK1R (up to 3 microg of SR140,333) and NK2R (up to 60 microg of SR48,968) antagonists tested failed to significantly affect responses to the noxious visceral stimulus. However, coadministration of 3 microg of SR140,333 and 60 microg of SR48,968 (both i.th.) significantly reduced responses to noxious CRD (p < 0.05 versus vehicle). The NK3R antagonist (60 microg of SR142,801) significantly reduced responses to noxious CRD when given alone to either hyperalgesic (zymosan-treated) or normal (saline-treated) rats (p < 0.05 versus vehicle for both groups). Responses of rats receiving the NK3R antagonist in combination with either the NK1R or the NK2R antagonist were not different from rats receiving the NK3R antagonist alone. These results suggest that activation of spinal NK1R and NK2R, presumably by their endogenous ligands (substance P and neurokinin A), maintain visceral hyperalgesia and support the notion that activation of NK3R (presumably by neurokinin B) is pronociceptive.
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PMID:Combinations of neurokinin receptor antagonists reduce visceral hyperalgesia. 1156 Oct 69

We have used a novel technology (NovoStar from BMG Labtechnologies) for the study of the Ca2+ signalling of the human tackykinin NK1 (hNK-I receptor). The NovoStar is a microplate reader based on fluorescence and luminescence. The instrument implements a robotic pipettor arm and two microplate carriers, typically one for samples and one for cells. The robotic pipettor arm can transfer sample (agonist or antagonist) from the sample plate or other liquid containers to the cell plate, facilitating the study of Ca2+ signalling to such a degree that the instrument can be used for Medium Throughput Screening (MTS). Using the NovoStar we have found the molecular pharmacology of the NK1 receptor to be comparable to that observed in classical signal transduction assays. Thus, we have observed an EC50 value of 3 nM for substance P induced Ca2+ response. This value corresponds well with previously published values for substance P induced IP and cAMP turnover. [1] Using the NovoStar technology we have studied the pharmacological profile of the well known non-peptide NKI receptor antagonists CP96,345 and SR140,333 [2,3] in respect of inhibition of the Ca2+ response induced by substance P. Interestingly, the antagonistic potency of the antagonists depended greatly on the experimental design, e.g., a dependency of timing in the addition of antagonists vs. agonist was noted. Also, metal-ion site engineered NK1 receptors [2] were tested for the ability of metal-ions to inhibit signalling. It is concluded that the NovoStar is a reliable tool for the study of receptor Ca2+ signalling, both as a research tool and as a MTS system.
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PMID:Novel method for the study of receptor Ca2+ signalling exemplified by the NK1 receptor. 1250 19

Neuroimmune interactions are important in airway diseases such as asthma. We evaluated the role of the tachykinin NK(1) receptor in the contractile response of isolated trachea from tachykinin NK(1) receptor wild type (WT) and knockout (KO) mice, to the antigen ovalbumin and the contractile agonist serotonin (5-hydroxytryptamine). One percent ovalbumin induced contractions of tracheas obtained from ovalbumin-immunized and exposed mice. The tracheas from WT animals showed larger contractions compared to the KO mice. Tracheas from sensitized and ovalbumin-exposed animals released 5-hydroxytyptamine upon addition of ovalbumin. No higher levels of 5-hydroxytryptamine were released from tracheas of WT animals. Tracheas of non-sensitized animals did not release 5-hydroxytryptamine upon ovalbumin challenge. Responses to ovalbumin were abrogated by methysergide, a broad 5-hydroxytryptamine receptor antagonist. Exogenous 5-hydroxytryptamine contracted tracheas but WT tracheas responded significantly more. Atropine and tetrodotoxin (TTX) reduced 5-hydroxytryptamine-induced contractions of the WT tracheas, while they did not affect 5-hydroxytryptamine-induced contractions of KO tracheas. 5-Hydroxytryptamine-induced contractions from atropine- or TTX-treated WT tracheas did not differ significantly from the contractions of the KO tracheas. Single tachykinin NK(1) receptor antagonists SR140,333 and RP67,580 had no effect on 5-hydroxytryptamine-induced contractions. In conclusion, the 5-hydroxytryptamine-induced tracheal contraction includes a cholinergic mechanism that requires the presence of the tachykinin NK(1) receptor.
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PMID:Role of the tachykinin NK(1) receptor in mediating contraction to 5-hydroxytryptamine and antigen in the mouse trachea. 1691 85

Contact hypersensitivity (CHS) is a type of cutaneous inflammation that is exacerbated by neurogenic factors. Both mu- and kappa-opioids enhance CHS to a greater extent in females than males. It was hypothesized that potentiated neurokinin 1 (NK1) receptor signaling following opioid treatment accounts for sex differences in the magnitude of CHS. Following morphine or spiradoline treatment the NK1 receptor antagonist SR140,333 significantly attenuated the magnitude of CHS in females but not males. By contrast, the NK2 antagonist SR48968 had no effect on morphine modulation of CHS. Taken together, these data indicate that NK1 receptor signaling is a key mediator of sex differences in opioid-induced enhancement of CHS.
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PMID:Neurokinin 1 receptor signaling mediates sex differences in mu and kappa opioid-induced enhancement of contact hypersensitivity. 1702 55