Actin crosslinking controls mobility, microtubule crosslinkers control co-localization in a composite cytoskeletal network*

Actin and microtubule filaments are cytoskeletal biopolymers with various vital roles in the cell. Despite decades of studying them separately, they have recently been shown to interact in networks mechanically and chemically. Here, we are interested in the composite network mechanics and mobility as the actin and microtubules are increasingly crosslinked. We use biotin-NeutrAvidin crosslinkers to irreversibly crosslink actin and MAP65, an antiparallel microtubule crosslinker to bundle microtubules. Cytoskeleton networks are imaged over time using fluorescent microscopy and the mobility characteristics are measured. We find that actin crosslinkers tune the mobility of this composite network, while microtubule crosslinkers can control the co-localization of actin and microtubules.