Lack of coupling of D-2 receptors to adenylate cyclase in GH-3 cells exposed to epidermal growth factor. Possible role of a differential expression of Gi protein subtypes
| Autor: | C, Missale, F, Boroni, L, Castelletti, R, Dal Toso, N, Gabellini, S, Sigala, P, Spano |
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| Rok vydání: | 1991 |
| Předmět: |
Potassium Channels
Quinpirole Base Sequence Epidermal Growth Factor Receptors Dopamine D2 Dopamine Cell Membrane Colforsin Dopamine Agents Molecular Sequence Data DNA Rubidium Prolactin Rats Receptors Dopamine GTP-Binding Proteins Cyclic AMP Tumor Cells Cultured Animals Dopamine Antagonists Amino Acid Sequence Ergolines Neurotensin Adenylyl Cyclases Vasoactive Intestinal Peptide |
| Zdroj: | The Journal of biological chemistry. 266(34) |
| ISSN: | 0021-9258 |
| Popis: | Exposure of GH-3 cells to epidermal growth factor for 4 consecutive days induced the expression of both D-2(415) and D-2(444) dopamine-receptor isoforms. Epidermal growth factor also promoted a remarkable increase in the content of Gi3 protein, which is responsible for receptor-induced activation of potassium channels in GH-3 cells. D-2 receptors in this model apparently activate a specific transducing pathway, leading to opening of potassium channels and inhibition of prolactin release by cAMP-independent mechanisms. This is shown by: 1) the selective D-2 agonist quinpirole, while inactive on vasoactive intestinal peptide-induced prolactin release, strongly inhibited the hormone secretion induced by neurotensin; 2) quinpirole, up to 100 microM, did not inhibit cAMP production evoked by vasoactive intestinal peptide both in intact cells and in broken cell membrane preparations; and 3) quinpirole and other D-2 agonists strongly potentiated Rb+ efflux when measured in a nominally calcium-free reaction solution containing 100 mM potassium (voltage-dependent component), but did not modify Rb+ efflux if measured in a reaction solution containing 1 mM calcium and 5 mM potassium (calcium-activated, cAMP-dependent component). |
| Databáze: | OpenAIRE |
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