  The microtubule (MT) motor Kip3p is very processive kinesin that promotes
catastrophes and pausing in particular on cortical contact. These properties
explain the role of Kip3p in positioning the mitotic spindle in budding yeast
and potentially other processes controlled by kinesin-8 family members. We
present a theoretical approach to positioning of a MT network in a cell. In
order to explore the underlying mechanism we introduce an idealized system of
two MTs connected by a microtubule organizing center (MTOC). The dynamics of
Kip3p is modeled by interacting stochastic particles, which allows us to study
the effects of motor-induced depolymerization under spatial confinement. We
find that localization in the middle of the system is realized in a parameter
regime where the motor densities on the MTs are increasing with the distance
from the MTOC. Localization at an asymmetric position is also possible by
tuning the kinesin input rates at the MT minus ends or attachment rates
depending on different compartments of the cell.
