Movement protein that is involved in local cell-cell movement via plamodesmata. At least five viral proteins, CP, CPm, p6, p64 and Hsp70h are essential for cell-cell movement. Also plays a role in virion formation. Together with Hsp70h and CPm, encapsidates the 5'-terminal portion of the viral genome. Integral virion tail component. The N-terminus is exposed at the virion surface, whereas the C-terminus is embedded in the virion.