Participates in the transport of viral genome to neighboring plant cells directly through plasmodesmata, without any budding (By similarity). TGBp2 and TGBp3 are necessary for intracellular delivery of TGBp1-containing vRNPs to plasmodesmata (By similarity). Can gate plasmodesmata and increase their size exclusion limit (PubMed:15608333). Induces host actin cytoskeleton network thickening, which probably plays a major role in virus cell-to-cell movement (By similarity). Interacts with movement protein TGB2 (PubMed:12093178, PubMed:15608333). TGB1-TGB3-TGB2 complex formation is enhanced by ATP hydrolysis (By similarity). Probably localizes to plasmodesmata-associated membrane compartments called peripheral membrane bodies (PMBs). Associates with host actin filaments. The 2nd transmembrane domain is involved in plasmodesmata targeting. Belongs to the virgaviridae TGB3 movement protein family.