| The members of the G protein coupled receptor family are distinguished by their slow transmitting response to ligand binding. These seven transmembrane proteins include the adrenergic, serotonin and dopamine receptors. The effect of the signaling molecule can be excitatory or inhibitory depending on the type of receptor to which it binds. Members of the AArrestin family regulate receptor binding to G proteins. AArrestins have been found to be located at postsynaptic sites, where they are thought to act in concert with ARK (ARK1, also designated GRK 2, or ARK2, also designated GRK 3) to regulate G protein-coupled neurotransmitter receptors. Expression of AArrestin-1 and AArrestin-2 is seen predominantly in spleen and neuronal tissues. It has been shown that AArrestin-1 expression is modulated by intracellular cAMP, which may be a novel mechanism for the regulation of receptor-mediated responses. |
