Cowpea mosaic virus (CPMV) moves from cell to cell as virus particles which are translocated through a plasmodesmata-penetrating transport tubule made up of viral movement protein (MP) copies. To gain further insight into the roles of the viral MP and capsid proteins (CP) in virus movement, full-length and truncated forms of the IMP were expressed in insect cells using the baculovirus expression system. Using ELISA and blot overlay assays, affinity purified IMP was shown to bind specifically to intact CPMV virions and to the large CP, but not to the small CP. This binding was not observed with a C-terminal deletion mutant of the IMP, although this mutant retained the capacity to bind to other MP molecules and to form tubules. These results suggest that the C-terminal 48 amino acids constitute the virion-binding domain of the MP.
- tubular structures