  Inside cells, cargos such as vesicles and organelles are transported by
molecular motors to their correct locations via active motion on cytoskeletal
tracks and passive, Brownian diffusion. During the transportation of cargos,
motor-cargo complexes (MCC) navigate the confining and crowded environment of
the cytoskeletal network and other macromolecules. Motivated by this, we study
a minimal two-state model of motor-driven cargo transport in confinement and
predict transport properties that can be tested in experiments. We assume that
the motion of the MCC is directly affected by the entropic barrier due to
confinement if it is in the passive, unbound state, but not in the active,
bound state where it moves with a constant bound velocity. We construct a
lattice model based on a Fokker Planck description of the two-state system,
study it using a kinetic Monte Carlo method and compare our numerical results
with analytical expressions for a mean field limit. We find that the effect of
confinement strongly depends on the bound velocity and the binding kinetics of
the MCC. Confinement effectively reduces the effective diffusivity and average
velocity, except when it results in an enhanced average binding rate and
thereby leads to a larger average velocity than when unconfined.
