Title: Spatial cytoskeleton organization supports targeted intracellular transport,
Abstract: The efficiency of intracellular cargo transport from specific source to
target locations is strongly dependent upon molecular motor-assisted motion
along the cytoskeleton. Radial transport along microtubules and lateral
transport along the filaments of the actin cortex underneath the cell membrane
are characteristic for cells with a centrosome. The interplay between the
specific cytoskeleton organization and the motor performance realizes a
spatially inhomogeneous intermittent search strategy. In order to analyze the
efficiency of such intracellular search strategies we formulate a random
velocity model with intermittent arrest states. We evaluate efficiency in terms
of mean first passage times for three different, frequently encountered
intracellular transport tasks: i) the narrow escape problem, which emerges
during cargo transport to a synapse or other specific region of the cell
membrane, ii) the reaction problem, which considers the binding time of two
particles within the cell, and iii) the reaction-escape problem, which arises
when cargo must be released at a synapse only after pairing with another
particle. Our results indicate that cells are able to realize efficient search
strategies for various intracellular transport tasks economically through a
spatial cytoskeleton organization that involves only a narrow actin cortex
rather than a cell body filled with randomly oriented actin filaments.