The efficiency of intracellular transport of cargo from specific source to target locations is strongly dependent upon molecular motor assisted motion along cytoskeleton filaments, microtubules and actin filaments. 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. Here we show that this specific URLanization for ballistic transport in conjunction with intermittent diffusion realizes a spatially inhomogeneous intermittent search strategythat is in general optimal for small thicknesses of the actin cortex. We prove optimality in terms of mean first passage times for three different, frequently encountered intracellular transport tasks: i) the narrow escapeproblem (e.g. transport of cargo to a synapse or other specific region of the cell membrane, ii) reaction kinetics enhancement (e.g. binding of a mobile particle with a immobile or mobile target within the cell, iii) the reaction-escape problem (e. g. release of cargo at a synapse after intracellular vesicle pairing. The results indicate that living cells realize optimal search strategies for various intracellular transport problems %DIFDELCMD < {\it %%% economically through a spatial URLanization that involves  only a narrow actin cortex rather than a cell body filled with randomly oriented actin filaments.
We consider random search processes alternating stochastically between diffusion and ballistic motion, in which the distribution function of ballistic motion directions varies from point to point in space. The specific space dependence of the directional distribution together with the switching rates between the two modes of motion establishes a spatially inhomogeneous search strategy. We show that the mean first passage times for several standard search problems - narrow escape, reaction partner finding, reaction-escape - can be minimized with a directional distribution that is reminiscent of the URLanization of the cytoskeleton filaments of cells with a centrosome: radial ballistic transport from center to periphery and back, and ballistic transport in random directions within a concentric shell of thickness \Delta_{\rm opt that living cells realize efficient search strategies for various intracellular transport problems %DIFDELCMD < {\it %%% economically through a spatial URLanization that involves radial microtubules in the central region and only a narrow actin cortex rather than a cell body filled with randomly oriented actin filaments.
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The efficiency of intracellular transport of cargo from specific source to target locations is strongly dependent upon molecular motor assisted motion along cytoskeleton filaments, microtubules and actin filaments. 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. Here we show that this specific URLanization for ballistic transport in conjunction with intermittent diffusion realizes a spatially inhomogeneous intermittent search strategythat is in general optimal for small thicknesses of the actin cortex. We prove optimality in terms of
We consider random search processes alternating stochastically between diffusion and ballistic motion, in which the distribution function of ballistic motion directions varies from point to point in space. The specific space dependence of the directional distribution together with the switching rates between the two modes of motion establishes a spatially inhomogeneous search strategy. We show that the
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three different, frequently encountered intracellular transport tasks: i) the narrow escapeproblem (e.g. transport of cargo to a synapse or other specific region of the cell membrane, ii) reaction kinetics enhancement (e.g. binding of a mobile particle with a immobile or mobile target within the cell, iii) the
several standard search problems - narrow escape, reaction partner finding,
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problem (e. g. release of cargo at a synapse after intracellular vesicle pairing. The results indicate
- can be minimized with a directional distribution that is reminiscent of the URLanization of the cytoskeleton filaments of cells with a centrosome: radial ballistic transport from center to periphery and back, and ballistic transport in random directions within a concentric shell of thickness \Delta_{\rm opt
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optimal
efficient
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economically
economically
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radial microtubules in the central region and