May play an important role in cardiac antiarrhythmia via the strong suppression of voltage-gated L-type Ca(2+) currents. Regulates voltage-dependent L-type calcium channel subunit alpha-1C trafficking to the cell membrane. Inhibits cardiac hypertrophy through the calmodulin-dependent kinase II (CaMKII) pathway. Inhibits phosphorylation and activation of CAMK2D (By similarity). Interacts with Calmodulin preferentially to the inactive, GDP-form. Interacts with CAMK2D and CACNB2. Interaction with CACNB2 regulates the trafficking of CACNA1C to the cell membrane (By similarity). Belongs to the small GTPase superfamily. RGK family.