Fig. 4.

Myosin force production and force-sensing. (A) Depending on their relative orientation at the CCP base, myosin-I might exert force pushing the actin meshwork toward the cytoplasm (driving elongation) or compressing the meshwork toward the CCP center (driving constriction and scission). (B) Some myosin-I isoforms serve as force producers, increasing their power output under high load. Others act as force sensors, with their motor activity stalling under small load forces and remaining tightly bound under high forces. It is not known what type of behavior describes the myosin-I isoforms which are involved in CME.