These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Evaluation of a purification procedure for the muscarinic receptor for the purpose of quantitative receptor assays of anticholinergics. Part B: The solubilized receptor.
    Author: Smisterová J, Ensing K, de Boer J, de Zeeuw RA.
    Journal: Prep Biochem; 1995 Nov; 25(4):223-51. PubMed ID: 8570570.
    Abstract:
    For the purpose of quantitative receptor assays, a three-step solubilization procedure including three optimization sets for muscarinic receptor from calf striatum was developed. The first step includes the extraction of the P2-pellet with n-hexane and consequently with 2 M NaCl. By the latter, 39% of non-receptor proteins was extracted. The resulting pellet (NaCl-pellet), enriched in muscarinic receptors by a factor of 1.5-1.7, was solubilized with 1% digitonin. The binding parameters of the solubilized receptor were determined for the tertiary 3H-dexetimide (3H-DEX) and the quaternary 3H-N-methylscopolamine (3H-NMS). The resulting receptor density measured with 3H-dexetimide was lower (43.3% of that for the NaCl-pellet) than that for 3H-N-methyl-scopolamine (56.7%). The treatment with digitonin preserved the high affinity for 3H-N-methylscopolamine (Kd = 0.645 nM), however the affinity of 3H-dexetimide decreased after solubilization (Kd = 8.526 nM). The use of solubilized receptors in combination with hydrophilic 3H-NMS allows to increase the ratio specific/non-specific binding, since the non-specific binding for this ligand to the solubilized preparation is lower when compared with membrane-bound receptors. The above solubilization procedure was found preferable over directly solubilizing the P2-pellet since (a) the receptor density for 3H-NMS was higher for the solubilized NaCl-pellet by a factor of about 1.7, and (b) the treatment of the P2-pellet with digitonin resulted in a lowering of the Kd to 2.422 nM. However, with respect to the plasma effect on the ligand binding, both solubilized preparations give similar results. The use of the solubilized NaCl-pellet or the P2-pellet can considerably improve the quantitative receptor assays of plasma samples. Unlike the membrane-bound receptor, a high volume of plasma, such as 400 microliters, can be added to the assay without any influence on the 3H-DEX binding when solubilized preparation is used.
    [Abstract] [Full Text] [Related] [New Search]