Abstract
Small molecule G-protein Arfs and its effector enzyme phospholipase D (PLD) are essential regulator for intracellular vesicular trafficking from endoplasmic reticulum to Golgi apparatus. We previously reported that intracellular application of brefeldin A, Exo1, and N-terminal peptide of Arf1, Arf1 inhibitors, depressed K+-current response induced by dopamine (DA) in Aplysia neurons. It is recently known that, Arf also play a role in regulation of recycling of several receptors at the cytoplasmic membrane in association with PLD. Therefore, we examined a possible involvement of the receptor endocytosis and recycling in regulation of the DA induced response. Intracellular application of α-synuclein, an inhibitor of PLD, significantly depressed the K+-current response to DA. Furthermore, intracellular application of dynamin inhibitory peptide, which inhibits the endocytosis of receptors, gradually augmented the DA induced K+-current response. In contrast, extracellular application of monensine, which inhibits the recycling of endocytosed receptors to the cytoplasmic membrane, gradually suppressed the DA induced K+-current response. These results suggest that Arf1 and PLD regulate the DA-induced K+-current response through recycling of the DA receptor to the cytoplasmic membrane. [J Physiol Sci. 2007;57 Suppl:S83]
