May play a role in lysosome motility. May play a role in chromosome segregation. (Microbial infection) Component of tomato mosaic virus (ToMV) RNA replication complexes. Required for tobamovirus multiplication, especially for efficient negative-strand RNA synthesis and viral RNA capping. Interacts with tubulin. Localizes with microtubules at the spindle mid-zone during mitosis. In double and triple mutants arl8a-1 arl8b-1 and arl8a-1 arl8b-1 arl8c-1, impaired multiplication of tomato mosaic virus (ToMV). Belongs to the small GTPase superfamily. Arf family.