TACC3 is a microtubule plus end-tracking protein that promotes axon elongation and also regulates microtubule plus end dynamics in multiple embryonic cell types.
Bottom Line: Using high-resolution live-imaging data on tagged +TIPs, we show that TACC3 localizes to the extreme microtubule plus end, where it lies distal to the microtubule polymerization marker EB1 and directly overlaps with the microtubule polymerase XMAP215.TACC3 also plays a role in regulating XMAP215 stability and localizing XMAP215 to microtubule plus ends.Taken together, our results implicate TACC3 as a +TIP that functions with XMAP215 to regulate microtubule plus end dynamics.
Affiliation: Department of Biology, Boston College, Chestnut Hill, MA 02467.Show MeSH
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Mentions: Evidence suggests that the TACC3-XMAP215 complex may generally be more stable than either protein individually, as each of them affects the protein level of the other in Xenopus whole-embryo lysates. This is consistent with studies in Caenorhabditis elegans showing that normal levels of TACC3 and XMAP215 orthologues are required to maintain the overall cytoplasmic signal of the other (Bellanger and Gonczy, 2003). Taken together, our data combined with others suggest a model in which XMAP215 and TACC3 form a complex in the cytoplasm that reduces protein turnover and also may increase their binding efficiency to MT plus ends, thus driving more effective MT polymerization (Figure 8). However, we also note that Xenopus TACC3 was first identified as a protein (originally named Maskin) that associates with CPEB to regulate translation in the oocyte (Stebbins-Boaz et al., 1999), and so it is also possible that TACC3 could be regulating XMAP215 protein synthesis rather than, or in addition to, protein stability.
Affiliation: Department of Biology, Boston College, Chestnut Hill, MA 02467.