Involved in intra- and inter-cellular trafficking through plasmodesmata (PD). Interacts with viral tomato spotted wilt virus (TSWV) movement protein NSM, which is involved in cell-to cell spread of viral genome and enlargement of the host plasmodesmata size exclusion limit (SEL). Accumulates intracellularly in a polarized fashion, into punctate spots at the cell periphery. Located at both orifices of the plasmodesmatal pore of adjacent cells. Can move through plasmodesmata. A number of isoforms are produced. According to EST sequences. Expressed in leaves (at protein level). The C-terminal part of the protein in required for plasmodesma localization. Extended C-terminus.