Functional small GTPase that acts as a negative factor controlling the light-dependent period shortening of circadian rhythms and light-induced phase resetting during the subjective night (PubMed:17683937). May protect the clock from excessive or mistimed light (PubMed:17683937). Suppresses red and blue light-mediated photomorphogenesis and is required for light-controlled inhibition of endoreplication and tolerance to salt stress (PubMed:23144185). The entrainment of the circadian clock is independent from the other pleiotropic effects (PubMed:23144185). Could be a regulator of seedling establishment (PubMed:23144185). The localization is not affected by light, but the nuclear localization is essential for the circadian function. Not regulated by the circadian clock. Short-period phenotype even in darkness and short hypocotyls in response to red and blue light but not to far-red light (PubMed:17683937). Altered cell shape and increased ploidy levels at the seedling stage (PubMed:23144185). Hypersensitivity to salt stress (PubMed:23144185). Has a GTPase activity despite the replacement of the highly conserved Glu-94 for His. Belongs to the small GTPase superfamily. The predicted gene At5g64810 has been split into 3 genes: At5g64810, At5g64813 and At5g64816.