Certain cells bear tiny hair-like structures called cilia, which beat in wave-like patterns. The mechanism underlying this behaviour is unknown, but researchers have succeeded in mimicking it with bundles of protein filaments.

Zvonimir Dogic and his colleagues at Brandeis University in Waltham, Massachusetts, built the in vitro system from just three components. They used microtubules (MTs), the filaments that form the backbone of cilia; kinesin motors, the protein complexes that bind to and slide along MTs; and polyethylene glycol, which bundles the MTs together. The authors found that their bundles, when anchored at one end, beat much less frequently than cilia — which have more than 650 proteins — but synchronize their beating at high density.

The authors suggest that the sliding kinesin motors, which were engineered to bind to two adjacent MTs, move these MTs in opposite directions, resulting in the beating motion.

Science 333, 456–459 (2011)