Abstract
A group of microtubule (MT)-associated proteins, called plus end tracking proteins (+Tips), associates specifically with growing MT plus ends. Recently, several +Tips are discovered in plants, but the functions have not been well understood.
End-Binding 1 (EB1) is a member of +Tips highly conserved in eukaryotes. Arabidopsis thaliana has three EB1 proteins (EB1a, EB1b, and EB1c) although functional conservation and divergence among Arabidopsis EB1 members are still unclear. In this study, we found that EB1c is expressed mainly in meristematic cells and the protein contains a bipartite nuclear localization signal in its unique C-terminal tail region. The eb1c cells were compromised the alignment of spindle and phragmoplast microtubules. Complementation tests indicated that the unique C-terminal tail of EB1c was necessary for full rescue of this eb1c defect. These results suggest that an EB1c has evolved to function preferentially on the spindle microtubules by accumulating in the prophase nucleus.
