This family includes a variety of movement proteins (MP)s. The MP is necessary for the initial cell-to-cell movement during the early stages of a viral infection. This movement is active, and it is known that the MP interacts with the plasmodesmata and possesses the ability to bind to RNA to achieve its role [1]. This family also includes consists of virus movement proteins from the caulimovirus family. It has been suggested in cauliflower mosaic virus that these proteins mediated viral movement by modifying plasmodesmata and forming tubules in the channel that can accommodate the virus particles [2] and references therein. The family contains a conserved DXR motif that is probably functionally important.

1: Effects of terminal deletion mutations on function of the movement protein of tobacco mosaic virus. Gafny R, Lapidot M, Berna A, Holt CA, Deom CM, Beachy RN; Virology 1992;187:499-507. PMID:1546450

2: The movement proteins of cowpea mosaic virus and cauliflower mosaic virus induce tubular structures in plant and insect cells. Kasteel DT, Perbal MC, Boyer JC, Wellink J, Goldbach RW, Maule AJ, van Lent JW; J Gen Virol 1996;77:2857-2864. PMID:8922481

3: Characterization of cassava vein mosaic virus: a distinct plant pararetrovirus. Calvert LA, Ospina MD, Shepherd RJ; J Gen Virol 1995;76:1271-1278. PMID:7730813