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: Precoupling of alpha-2B adrenergic receptors and G-proteins in transfected PC-12 cell membranes: influence of pertussis toxin and a lysine-directed cross-linker.
    Author: Shi AG, Deth RC.
    Journal: J Pharmacol Exp Ther; 1994 Dec; 271(3):1520-7. PubMed ID: 7996466.
    Abstract:
    The ability of pertussis toxin (PTX) pretreatment to alter the binding of [3H]rauwolscine (RAU) to alpha-2B adrenergic receptors expressed in PC12 cells was examined. PTX caused a 30% increase in the Bmax for [3H]RAU and reduced its KD, whereas in the added presence of Na+ and Gpp(NH)p binding was increased to 75% above the level in untreated membranes. Because all three agents act to reduce receptor/G-protein affinity, the increased binding may reflect extensive precoupling of the alpha-2B receptor. The affinity of the agonist epinephrine in displacing [3H]RAU was normally reduced by both Na+ and Gpp(NH)p; however, in PTX-treated membranes the effect of Gpp(NH)p was eliminated, and Na+ remained effective. The lysine-directed cross-linking reagent ethyleneglycol bis(succinimidyl)succinate (EGS) was utilized in an attempt to cross-link precoupled receptor and G-protein. Maximal [3H]RAU binding was reduced by EGS in a time- and dose-dependent manner, and this action was reversed by prior incubation with Na+ and Gpp(NH)p, suggesting that EGS did indeed cross-link receptor and G-protein. RAU and epinephrine each provided protection against the effect of EGS. The inclusion of Na+ and Gpp(NH)p during [3H]RAU binding studies was able to restore maximal binding in EGS-treated membranes to the same level as untreated membranes. These results indicate that in the absence of Na+ and Gpp(NH)p at least 40% of the total alpha-2B adrenergic receptors in these membranes exist as a precoupled receptor/G-protein complex which fails to bind [3H]RAU.
    [Abstract] [Full Text] [Related] [New Search]