Table 4.

Mechanistic modes of Arp2/3 and myosin coordination across systems.

Mode	Representative system	Molecular basis	Evidence and interpretation
Direct/modular activation	Budding-yeast endocytosis	Type-I myosin motor and actin-assembly activation activities are separable but locally coordinated (Hill et al., 2024b).	Genetic and cellular evidence; organism-specific and not established for mammalian myosin-I.
Recruitment control	Fission-yeast endocytosis	Ank1 restricts nonspecific Myo1 membrane binding and spatially limits endocytic activity (Willet et al., 2023).	Genetic and imaging evidence for regulatory coupling; not proof of a conserved mammalian activation mechanism.
Structural anchoring	Mammalian clathrin-mediated endocytosis	Myo1E couples cortical actin to membrane and responds to membrane tension (Smith et al., 2026).	Imaging and perturbation support load-dependent mechanical coordination, not direct Arp2/3 activation.
CARMIL-mediated bridging	Dictyostelium discoideum	CARMIL links type-I myosin, capping protein, and Arp2/3 through distinct interactions (Jung et al., 2001).	Scaffold-mediated molecular coupling supported by biochemical interaction data.
Mechanical/signaling coupling	Migrating cells and neuronal growth cones	Arp2/3-dependent protrusion and NMII-dependent contractility interact through actin flow, pressure, adhesion, and Rho signaling (Yang et al., 2012; Patel et al., 2021).	Spatially separated modules; cell perturbation supports mechanical cross-talk rather than stable binding.
Reconstituted mechanical synergy	Actin-comet system	myosin-I remodels Arp2/3-dependent branched networks and increases pushing efficiency (Xu et al., 2024).	Purified reconstitution provides strong evidence for context-dependent synergy in the tested system.