Emory University graduate student Ekram Towsif and Professor Shashank Shekhar have uncovered groundbreaking insights into the dynamics of actin filaments and the multifunctional actin-binding protein cyclase-associated protein (CAP). Using cutting-edge biophysical techniques, including microfluidics-assisted TIRF microscopy and multispectral single-molecule imaging, their research reveals CAP’s previously unknown role as a processive depolymerase at the barbed ends of actin filaments. This discovery challenges conventional understanding, as CAP was traditionally associated with filament pointed ends and monomer recycling. The team also demonstrated that CAP interacts with key regulators at barbed ends, enhancing the processivity of formin (an elongator) while destabilizing capping protein (a blocker). These findings, published in the Proceedings of the National Academy of Sciences (PNAS), establish CAP as a central player in actin dynamics and open new avenues for exploring its regulatory mechanisms in cellular processes such as motility, structure, and metastasis. See the full article here: https://www.pnas.org/doi/abs/10.1073/pnas.2411318122?af=R