"Search-and-capture" of microtubules through plus-end-binding proteins (+TIPs)

The generation of a polarized microtubule organization is critically important for proper cellular functions, such as cell division, differentiation and migration. Microtubules themselves are highly dynamic structures, and this dynamic property is temporally and spatially regulated within cells, especially at their plus ends. To explain how microtubules set up and make contacts with cellular structures, a "search-and-capture" mechanism has been proposed, in which the microtubule plus ends dynamically search for and capture specific sites, such as mitotic kinetochores and cell cortex. To date, several classes of proteins have been shown to be associated with microtubule plus ends in a wide range of organisms from fungi to humans and to play critical roles in the "search-and-capture" mechanism. In this review, we overview our current understanding of the "plus-end-binding proteins" (+TIPs), including APC (adenomatous polyposis coli) tumor suppressor protein, cytoplasmic linker proteins (CLIPs), CLIP-associating proteins (CLASPs), cytoplasmic dynein/dynactin, and EB1, an APC-interacting protein.