ADP‐ and epinephrine‐elicited release of [3H]guanylylimododiphosphate from platelet membranes

FEBS Letters

Motulsky, Harvey J.¹  Insel, Paul A.¹ 

[1]Division of Pharmacology M013H, University of California, San Diego, La Jolla, CA 92093, USA

关键词: Alpha2-adrenergic receptor;    ADP receptor;    Adenylate cyclase;    Nucleotide-binding protein;    Guanine nucleotide;   

DOI  :  10.1016/0014-5793(83)80008-8

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Epinephrine-promoted release of [³H]guanylylimidodiphosphate ([³H]Gpp(NH)p) from human platelet membranes has been used to probe the interactions between alpha₂-adrenergic recpetors and N_i, the guanine nucleotide binding protein that couples those receptors to an inhibition of adenylate cyclase activity. We show here that ADP, which also acts through specific platelet receptors to inhibit adenylate cyclase activity, also promotes the release of [³H]Gpp(NH). The amount of [³H]Gpp(NH)-release elicited by epinephrine and by ADP together is equal to the sum of the amounts released by the two agents acting individually. Furthermore the maximal amounts of [³H]Gpp(NH)-release elicited by each of the two agents approximates the numbers of receptors for ADP and epinephrine present in the platelet membranes. These results suggest that the two receptor types interact with distinct portions of the pool of N_i molecules and that each receptor initiates guanine-nucleotide exchange on a single molecule of N_i.

【 授权许可】

Unknown