The controlling mechanisms of basal myosin oscillation

Basal myosin oscillation is barely dependent on actomyosin cortical tension, indicating that oscillation is mainly from biochemical reaction. During basal myosin oscillation, Rho1 proteins and Rho1 activity are mainly distributed and enriched at and near basal junction and the major control of basal myosin oscillation is the flow movement of oscillatory ROCK signals from basal junction to medio-basal cortex. This ROCK flow movement is initiated from the transient interaction of ROCK with active Rho1 at and near basal junction, thus leading to the opening and activation of ROCK kinase capability. During the membrane-medial flow movement, ROCK kinase activity mediates the accumulation and thus the amplification of ROCK signals. This positive signal amplification turns on the phosphorylation of myosin regulatory light chain (MRLC), which governs the dynamic redistribution of myosin phosphatase MBS. Finally, enriched MBS signals shut off both ROCK and myosin signals.