| Autor: |
J, Zhu, W, Li, M L, Toews, T D, Hexum |
| Rok vydání: |
1992 |
| Předmět: |
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| Zdroj: |
The Journal of pharmacology and experimental therapeutics. 263(3) |
| ISSN: |
0022-3565 |
| Popis: |
The effect of neuropeptide Y (NPY) on adenylate cyclase activity and the role of G-proteins mediating NPY's effect were investigated in cultured bovine adrenal chromaffin cells. The equilibrium binding of [125I]NPY to sucrose gradient purified bovine adrenal medulla plasma membranes revealed high- (GTP gamma S sensitive) and low-affinity binding sites with calculated IC50 values of 0.27 nM and 0.14 microM, respectively. Inhibition of forskolin-stimulated cyclic AMP accumulation was dependent upon the NPY concentration (IC50 = 0.9 nM) and independent of cyclic AMP (cAMP) phosphodiesterase activity. NPY-related peptides, except peptide YY, and NPY fragments exhibited minimal inhibitory activity. The inhibitory effect of NPY on forskolin-stimulated adenylate cyclase activity was completely abolished by pretreatment of the cells with pertussis toxin (PTX). Incubation of membranes with PTX and [32P]nicotinamide adenine dinucleotide revealed a protein band with an apparent molecular mass of 41 kDa. The time course and dose dependence of PTX pretreatment for in vitro ADP-ribosylation were similar to those for PTX to attenuate the NPY effect on forskolin-stimulated adenylate cyclase activity. The direct relation between the NPY receptor and the PTX-sensitive G-protein was further shown by the ability of NPY to inhibit PTX-catalyzed in vitro ADP-ribosylation. ADP-ribosylation of the 41-kDa protein was partially inhibited by 5'-guanylylimidodiphosphate and further inhibited by high concentrations of NPY. An antibody against Gi1/i2 alpha 1 recognized two species of which a 41-kDa protein comigrated with the PTX substrate.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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