@article {Christensen169961, author = {Jenna R. Christensen and Kaitlin E. Homa and Meghan E. O{\textquoteright}Connell and David R. Kovar}, title = {Tropomyosin and α-actinin cooperation inhibits fimbrin association with actin filament networks in fission yeast}, elocation-id = {169961}, year = {2017}, doi = {10.1101/169961}, publisher = {Cold Spring Harbor Laboratory}, abstract = {We previously discovered that competition between fission yeast actin binding proteins (ABPs) for association with F-actin helps facilitate their sorting to different F-actin networks. Specifically, competition between actin patch ABPs fimbrin Fim1 and cofilin Adf1 enhances each other{\textquoteright}s activities, and rapidly displaces tropomyosin Cdc8 from the F-actin network. However, these interactions don{\textquoteright}t explain how Fim1, a robust competitor, is prevented from associating equally well with other F-actin networks. Here, with a combination of fission yeast genetics, live cell fluorescent imaging, and in vitro TIRF microscopy, we identified the contractile ring ABP α-actinin Ain1 as a key sorting factor. Fim1 competes with Ain1 for association with F-actin, which is dependent upon their residence time on F-actin. Remarkably, although Fim1 outcompetes both contractile ring ABPs Ain1 and Cdc8 individually, Cdc8 enhances the bundling activity of Ain1 10-fold, allowing the combination of Ain1 and Cdc8 to inhibit Fim1 association with contractile ring F-actin.}, URL = {https://www.biorxiv.org/content/early/2017/07/28/169961}, eprint = {https://www.biorxiv.org/content/early/2017/07/28/169961.full.pdf}, journal = {bioRxiv} }