This Project Grant award from the National Institute of General Medical Sciences (NIGMS) Biomedical Research and Research Training program (CFDA 93.859) will support research at the University of Texas Southwestern Medical Center to study the evolutionary diversification of cytoskeletal proteins and their specialized functions across tissue types and species. The $410,000 award, active from January 1, 2025 to December 31, 2029, will fund three distinct research projects. The first will investigate how evolution alters the canonical ARP2/3 complex, a critical actin nucleator, to tailor actin polymerization for tissue- and species-specific needs. The second will genetically dissect the novel functions of a young, non-canonical actin-related protein (ARP) that emerged in fruit flies and plays a role in fertility. The third will focus on rapidly evolving, non-canonical ARPs in mammals that form a complex, localize to actin in the testis, and are critical for shaping the sperm head. This research aims to provide molecular insight into how cytoskeletal protein diversification specializes cellular networks for specific contexts, extending beyond their core "housekeeping" functions.