The microtubule network provides an essential trackway for the rapid movement of vesicles around cells, and the microfilament network also contributes to the local organisation and movement of vesicles.
Motor proteins can move vesicles and organelles (described as cargo) along microfilaments (myosins) or along microtubules (kinesins and dyneins). Kinesin and most kinesin-related proteins move to the plus end of microtubules whereas dyneins move to the minus end.
The motor domains (heads) of these proteins convert ATP into work. Kinesin is a two-headed molecule and dyneins have two or three heads, which step along the microtubule in a coordinated fashion.
Association of the correct motor protein with a trafficking vesicle ensures that the vesicle will move towards the correct region of the cell. However, the mechanisms by which the correct motor protein is attached to a vesicle are unclear.