Differential effects of guanine nucleotides on kainic acid binding and on adenylate cyclase activity in chick optic tectum

FEBS Letters

Ramírez, Galo²  Souza, Diogo¹  Ramos, Milagros²  Paz, Murilo Monteiro¹ 

[1]Departamento de Bioquímica, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil

[2]Centro de Biología Molecular (CSIC-UAM), Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain

关键词: Kainic acid receptor;    Guanine nucleotide;    G protein;    Adenylate cyclase;    Chick optic tectum;    AC;    adenylate cyclase;    ACPD;    1-amino-cyclopentyl-1;    3-dicarboxylate;    AMPA;    α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate;    GDP-S;    guanosine-5′-O-2(2-thio) diphosphate;    GMP-PNP;    5′-guanylyl-imidodiphosphate;    KA;    kainic acid;    L-AP4;    l-2-amino-4-phosphonobutyrate;    NMDA;    N-methyl-d-asparate;   

DOI  :  10.1016/0014-5793(94)01208-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

In G protein-coupled receptors, neurotransmitter-induced binding of GTP to G proteins triggers the activation of effector systems while simultaneously decreasing the affinity of the transmitter for its specific binding site within the receptor—G protein complex. In the present study we show that, in the chick optic tectum, guanine nucleotides inhibit the binding of the glutamate analog, kainate, and activate adenylate cyclase by different mechanisms and acting on different sites. GMP-PNP, a non-hydrolyzable analog of GTP, binds tightly to G proteins so that the binding is stable even after exhaustive washing. By use of this property, we have prepared membrane samples in which G protein GTP-binding sites are pre-saturated with GMP-PNP. Experiments carried out with these membranes show that GMP-PNP, GDP-S and GMP inhibit the binding of [³H]kainate by interacting with site(s) unrelated to G proteins, whereas GMP-PNP activates adenylate cyclase activity by binding to G proteins.

【 授权许可】

Unknown