Microtubule organisation by motors and nonmotor microtubule–associated proteins

Microtubules are key components of the eukaryotic cytoskeleton. These stiff polymers often span the entire cell, provide structural support, and act as tracks for long-distance transport and force generators. Their organisation underlies the logistics of intracellular cargo transport, resistance to compressive loads, and polarity factor signalling. Microtubules are intrinsically dynamic and many factors that bind to the inside, outside, and ends of the microtubule modulate their properties. Passive crosslinkers can bundle two microtubules or align microtubules to the cell cortex and other cytoskeletal filaments, while molecular motors slide microtubules relative to each other, generating extensile or contractile forces, coalesce microtubule ends into asters, position and move microtubule superstructures within the cell, or drive bulk cytoplasmic flows. This review will summarise recent progress in our understanding of how microtubule organisers function and are regulated, which has been made possible through technical advances in structural biology and optical microscopy, increasingly complex reconstituted systems and insights from diverse cellular systems.