  Cooperative action of molecular motors is essential for many cellular
processes. One possible regulator of motor coordination is the
elasticity-mediated crosstalk (EMC) coupling between myosin II motors whose
origin is the tensile stress that they collectively generate in actin
filaments. Here, we use a statistical mechanical analysis to investigate the
influence of the EMC effect on the sarcomere - the basic contractile unit of
skeletal muscles. We demonstrate that the EMC effect leads to an increase in
the attachment probability of motors located near the end of the sarcomere
while, simultaneously, decreasing the attachment probability of the motors in
the central part. Such a polarized attachment probability would impair the
motors ability to cooperate efficiently. Interestingly, this undesired
phenomenon becomes significant only when the system size exceeds that of the
sarcomere in skeletal muscles, which provides an explanation for the remarkable
lack of sarcomere variability in vertebrates. Another phenomenon that we
investigate is the recently observed increase in the duty ratio of the motors
with the tension in muscle. We reveal that the celebrated Hill's equation for
muscle contraction is very closely related to this observation.
