Dynamic instability of microtubules as an efficient way to search in space.

During the formation of the mitotic spindle, dynamic microtubules search for chromosomes in the surrounding cytosol. The average time required to reach such "targets" is calculated within a simple model of dynamic instability. The values of the dynamic parameters that minimize this search time are also obtained. The results approximate well observations of the capture of chromosomes in prometaphase cells. Compared to usual reversible polymerization, dynamic instability reduces the time required to find a target by several orders of magnitude.