Nexin and sliding force

The doublets are cross-linked by Nexin and make contacts to the central pair of singlet MTs through radial spokes. These cross-links transmit a sliding force between the tubules. If an isolated axoneme is mildly proteolyzed (which removes Nexin) and ATP added, the tubules slide on each other, rather than bending. Remember dynein walks from + to - along a microtubule