Protein structure and functions are tightly regulated. Studying the integration of multiple modifications in single systems is a novel approach. Hisactophilin protein from Dictyostelium discoideum, is an actin binding protein that serves to induce formation of actin filaments and is regulated by protonation and myristoylation. Utilizing hisactophilin as a model, I determined the effect of pH and myristoyl-switching on actin binding and filament induction using fluorescence spectroscopy, light scattering, and time-course electron microscopy. Results revealed the accessible myristoyl group slows binding and the rate of actin polymerization compared to when the group is sequestered. Hisactophilin induces pH-dependent actin aggregates before reorganizing them into filaments and bundles. Hisactophilin mutants impact initial actin binding and the kinetics of the aggregated state. I determined the cooperativity of myristoylation and protonation as interdependent protein regulatory mechanisms, their impact on actin binding and proposed a novel mechanism for actin polymerization as a result of these integrated regulators. / NSERC