Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P08908 (5-HT1A)
 5,574 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have characterized and quantitated the lipids which are cosolubilized with serotonin 5-HT1A sites from sheep brain using 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS). Dialysis of the CHAPS extract produced a [3H]8-hydroxy(2-di-n-propylamino)tetralin [( 3H]8-OH-DPAT) binding vesicular preparation of the protein. Quantitative analysis of the lipids present in the CHAPS extract by HPTLC and transmittance-densitometry revealed extraction of phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylinositol (PI), phosphatidyl serine (PS) and phosphatidic acid (PA) in striking preference over cholesterol, galactosylceramides, sulfatides and sphingomyelin. All lipids present in the clear CHAPS-extract were coeluted with the [3H]8-OH-DPAT binding preparation were separated by centrifugation, 95-100% of the [3H]8-OH-DPAT binding protein was retained in the vesicle-containing pellet. The supernatant contained small amounts of cholesterol, PE and PC, but virtually no PS, PI, or PA, whereas the vesicular pellet contained all the lipids mentioned, indicating that PS, PI and PA are more tightly bound to the vesicles than PE, PC and cholesterol. SDS-PAGE analysis of the pellet revealed two major protein bands, at 58 kDa and 33.5 kDa, respectively. Our report outlines a simple and improved densitometric assay used for the first detailed analysis of lipids cosolubilized with an active, membrane protein, and also, a simple assay for CHAPS.
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PMID:Asymmetric extraction of membrane lipids by CHAPS. 214 3

[3H]5-Methyl-urapidil, a potent antihypertensive derivative of urapidil, binds to alpha 1A-adrenoceptors in rat brain cortex membranes with a dissociation constant (KD) of 0.89 nM and a Bmax of 116 fmol/mg protein. The ligand does not bind to purified liver cell membranes (alpha 1B-adrenoceptors). [3H]5-Methyl-urapidil also labels 5-HT1A receptors in brain membranes (KD: 0.84 nM and Bmax: 235 fmol/mg protein). (+/-)-Niguldipine, a novel 1,4-dihydropyridine with Ca2+-antagonistic as well as alpha 1A-adrenoceptor blocking properties, is a competitive inhibitor of [3H]5-methyl-urapidil binding to alpha 1A-adrenoceptors. In contrast to those for prazosin, the Ki values for niguldipine were highly dependent on the membrane protein concentration, indicating partitioning of niguldipine into hydrophobic compartments unavailable for alpha-adrenoceptor interaction. The extrapolated, 'true' Ki values were as follows: (+/-)-niguldipine: 0.298 nM, (-)-niguldipine: 3.12 nM, (+)-niguldipine: 0.145 nM.
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PMID:Stereoselective binding of niguldipine enantiomers to alpha 1A-adrenoceptors labeled with [3H]5-methyl-urapidil. 255 6

Insect cell expression systems are used to characterize signaling components such as G protein-coupled receptors. As such, one must know whether endogenous G proteins couple to non-native receptors. We examined G protein linkages after infection of Sporodoptera frugiperda (Sf9) cells with a baculovirus encoding the 5-HT1A receptor. Receptor expression was confirmed by immunoblot. Some of the receptors were functional, showing guanine nucleotide-sensitive binding to the specific agonist ligand [3H]8-hydroxy-2-(di-n-propylamino)-1,2,3,4-tetranaphthalene). Peak expression (approximately 150 fmol/mg of membrane protein) was attained approximately 72-96 h post-infection. 5-HT-increased covalent binding of [32P]GTP-azidoanilide to a 40 kDa band, which was identified as a G protein by nucleotide blocking, Mg2+ dependence, and immunoblot and immunoprecipitation studies. The band comigrated with 1) pertussis toxin substrate(s), and 2) a band recognized by two G(o) alpha antisera and one common to heterotrimeric G protein alpha-subunits, but not by sera specific for Gs alpha or G(i) alpha. Labeled species could be precipitated with a G(o) alpha antiserum. 5-HT-increased labeling of the band was prevented by preincubation with pertussis toxin. These studies suggest that the 5-HT1A receptor couples effectively to native insect cell G(o)-like proteins.
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PMID:Human 5-HT1A receptor expressed in insect cells activates endogenous G(o)-like G protein(s). 817 13

Previous studies by another group have suggested that the alpha 2-adrenergic receptor antagonist rauwolscine may function as an agonist at the serotonin1A (5-HT1A) receptor expressed in human brain. To directly test that hypothesis, we transfected the human 5-HT1A receptor cDNA into CHO cells and examined the ability of rauwolscine and its isomer, yohimbine, to inhibit ligand binding of [3H]-(+/-)-8-hydroxy-2-(di-n-propylamino)tetralin ([3H]8-OH-DPAT) and the activity of adenylyl cyclase in membranes derived from a single transformant that stably expresses approximately 225 fmol of 5-HT1A receptor/mg of membrane protein. Both ligands competitively antagonized the binding of [3H]8-OH-DPAT (Ki = 158 +/- 69 nM for rauwolscine and 690 +/- 223 nM for yohimbine), yielding shallow displacement curves consistent with agonist activity (Hill values = 0.69 +/- 0.2 for rauwolscine and 0.63 +/- 0.06 for yohimbine). Both ligands also inhibited forskolin-stimulated adenylyl cyclase activity in membranes derived from transfected (but not nontransfected) cells. For rauwolscine, the IC50 was 1.5 +/- 0.2 microM, and for yohimbine 4.6 +/- 1.0 microM, with activity ratios of 0.70 and 0.59, respectively, when compared to the full agonist serotonin. These studies demonstrated that rauwolscine and yohimbine are partial agonists for the human 5-HT1A receptor.
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PMID:Partial agonist properties of rauwolscine and yohimbine for the inhibition of adenylyl cyclase by recombinant human 5-HT1A receptors. 851 75

Although the subtypes of serotonin 5-HT1 receptors have distinct structure and pharmacology, it has not been clear if they also exhibit differences in coupling to cellular signals. We have sought to compare directly the coupling of 5-HT1A and 5-HT1B receptors to adenylyl cyclase and to the mitogen-activated protein kinase ERK2 (extracellular signal-regulated kinase-2). We found that 5-HT1B receptors couple better to activation of ERK2 and inhibition of adenylyl cyclase than do 5-HT1A receptors. 5-HT stimulated a maximal fourfold increase in ERK2 activity in nontransfected cells that express endogenous 5-HT1B receptors at a very low density and a maximal 13-fold increase in transfected cells expressing 230 fmol of 5-HT1B receptor/mg of membrane protein. In contrast, activation of 5-HT1A receptors stimulated only a 2.8-fold maximal activation of ERK2 in transfected cells expressing receptors at 300 fmol/mg of membrane protein but did stimulate a 12-fold increase in activity in cells expressing receptors at 3,000 fmol/mg of membrane protein. Similarly, 5-HT1A, but not 5-HT1B, receptors were found to cause significant inhibition of forskolin-stimulated cyclic AMP accumulation only when expressed at high densities. These findings demonstrate that although both 5-HT1A and 5-HT1B receptors have been shown to couple to G proteins of the Gi class, they exhibit differences in coupling to ERK2 and adenylyl cyclase.
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PMID:Differential coupling of serotonin 5-HT1A and 5-HT1B receptors to activation of ERK2 and inhibition of adenylyl cyclase in transfected CHO cells. 1038 67