The present invention provides methods and compositions for modulating the activities of metabotropic glutamate receptor intracellular signaling molecules. The present invention provides methods and compositions for modulating the activities of casein kinase I and/or cyclin-dependent kinase 5 in cells or tissues. The present invention provides methods of modulating the function of calcium channels in cells or tissues. The present invention provides methods of treating calcium channel dysfunction. The present invention provides methods of identifying agents that modulate the activities of the metabotropic glutamate receptor intracellular signaling molecules casein kinase I and/or cyclin-dependent kinase 5 for use in such treatments.