  Cells are complex structures which require considerable amounts of
organization via transport of large intracellular cargo. While passive
diffusion is often sufficiently fast for the transport of smaller cargo, active
transport is necessary to organize large structures on short timescales. The
main mechanism of this transport is by cargo attachment to motors which walk in
a directed fashion along intracellular filaments. There are a number of models
which seek to describe the motion of motors with attached cargo, from detailed
microscopic to coarse phenomenological descriptions. We focus on the
intermediate-detailed discrete stochastic hopping models, and explore how cargo
transport changes depending on the number of motors, motor interaction, system
constraints and rate formulations which are derived from common thermodynamic
assumptions. We find that, despite obeying the same detailed balance
constraint, the choice of rate formulation considerably affects the
characteristics of the overall motion of the system, with one rate formulation
exhibiting novel behavior of loaded motor groups moving faster than a single
unloaded motor.
