Kinesin motor protein dimer, molecular model. Kinesin is a motor protein that moves along microtubule filaments in cells. It does so by forming a dimer, the heads of which 'walk' along the microtubule. Here, the heads of the dimer are formed by two protein chains (orange and green, right; and pink and blue, left) that are attached by a 'neck' region (lower centre) where they coil together. This is not the alignment adopted when moving along a microtubule. The structure modelled here is based on studies of this kinesin in the brown rat (Rattus norvegicus).