  The cytoskeleton is an inhomogeneous network of semi-flexible filaments,
which are involved in a wide variety of active biological processes. Although
the cytoskeletal filaments can be very stiff and embedded in a dense and
cross-linked network, it has been shown that, in cells, they typically exhibit
significant bending on all length scales. In this work we propose a model of a
semi-flexible filament deformed by different types of cross-linkers for which
one can compute and investigate the bending spectrum. Our model allows to
couple the evolution of the deformation of the semi-flexible polymer with the
stochastic dynamics of linkers which exert transversal forces onto the
filament. We observe a $q^{-2}$ dependence of the bending spectrum for some
biologically relevant parameters and in a certain range of wavenumbers $q$.
However, generically, the spatially localized forcing and the non-thermal
dynamics both introduce deviations from the thermal-like $q^{-2}$ spectrum.
