Anillin Promotes Cell Contractility by Cyclic Resetting of RhoA Residence Kinetics. Budnar Srikanth,Husain Kabir B,Gomez Guillermo A,Naghibosadat Maedeh,Varma Amrita,Verma Suzie,Hamilton Nicholas A,Morris Richard G,Yap Alpha S Developmental cell RhoA stimulates cell contractility by recruiting downstream effectors to the cortical plasma membrane. We now show that direct binding by anillin is required for effective signaling: this antagonizes the otherwise labile membrane association of GTP-RhoA to promote effector recruitment. However, since its binding to RhoA blocks access by other effectors, we demonstrate that anillin must also concentrate membrane phosphoinositide-4,5-P (PIP) to promote signaling. We propose and test a sequential pathway where GTP-RhoA first binds to anillin and then is retained at the membrane by PIP after it disengages from anillin. Importantly, re-binding of membrane GTP-RhoA to anillin, regulated by the cortical density of anillin, creates cycles through this pathway. These cycles repeatedly reset the dissociation kinetics of GTP-RhoA, substantially increasing its dwell time to recruit effectors. Thus, anillin regulates RhoA signaling by a paradigm of kinetic scaffolding that may apply to other signals whose efficacy depends on their cortical dwell times. 10.1016/j.devcel.2019.04.031