  Many functional units in biology, such as enzymes or molecular motors, are
composed of several subunits that can reversibly assemble and disassemble. This
includes oligomeric proteins composed of several smaller monomers, as well as
protein complexes assembled from a few proteins. By studying the generic
spatial transport properties of such proteins, we investigate here whether
their ability to reversibly associate and dissociate may confer them a
functional advantage with respect to non-dissociating proteins. In uniform
environments with position-independent association-dissociation, we find that
enhanced diffusion in the monomeric state coupled to reassociation into the
functional oligomeric form leads to enhanced reactivity with distant targets.
In non-uniform environments with position-dependent association-dissociation,
caused e.g. by spatial gradients of an inhibiting chemical, we find that
dissociating proteins generically tend to accumulate in regions where they are
most stable, a process that we term 'stabilitaxis'.
