Coordinated formation and disassembly of a contractile actomyosin network mediates content release from large secretory vesicles. A cycle of actin assembly and subsequent depolymerization occurs on a contracting secretory vesicle. The composition of the secretory vesicle membrane is different from the apical salivary gland membrane (a). After vesicle fusion to the apical membrane, active Rho1 is enriched on the vesicle surface (b). Active Rho1 then triggers assembly of the actin coat via Dia (c), which in turn recruits RhoGAP71E (d). RhoGAP71E inactivates Rho1 (e), resulting in actin disassembly (f) and allowing for actomyosin-mediated vesicle constriction (g). Fusion of the vesicle recruits activated Rho1 from the apical membrane (h), leading in parallel to the actin nucleation and depolymerization cycle, to the recruitment of Rok, which triggers myosin II activation. Although Rho1 regulates the recruitment of myosin II to the vesicle, the dynamics of the actin coat are myosin independent. Activities of both arms are essential for vesicle constriction.