  Cell membranes are anchored to the cytoskeleton via immobile inclusions. We
investigate the effect of such anchors on the in-plane dynamics of a fluid
membrane and mobile inclusions (proteins) embedded in it. The immobile
particles lead to a decreased diffusion coefficient of mobile ones and suppress
the correlated diffusion of particle pairs. Due to the long-range,
quasi-two-dimensional nature of membrane flows, these effects become
significant at a low area fraction (below one percent) of immobile inclusions.
