In vivo movement of the type V myosin Myo52 requires dimerisation but is independent of the neck domain.

Intracellular movement is a fundamental property of all cell types. Many organelles and molecules are actively transported throughout the cytoplasm by molecular motors, such as the dimeric type V myosins. These possess a long neck, which contains an IQ motif, that allow it to make 36-nm steps along the actin polymer. Live cell imaging of the fission yeast type V myosin Myo52 reveals that the protein moves rapidly throughout the cytoplasm. Here, we describe analysis of this movement and have established that Myo52 moves long distances on actin filaments in an ATP-dependent manner at approximately 0.5 mum/second. Myo51 and the microtubule cytoskeleton have no discernable role in modulating Myo52 movements, whereas rigour mutations in Myo52 abrogated its movement. We go on to show that, although dimerisation is required for Myo52 movement, deleting its neck has no discernable affect on Myo52 function or velocity in vivo.