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The microtubule cytoskeleton is a dynamic structure in which the lengths of the microtubules are tightly regulated. One regulatory mechanism is the depolymerization of microtubules by motor proteins in the kinesin-13 family. These proteins are crucial for the control of microtubule length in cell division, neuronal development and interphase microtubule(More)
MCAK belongs to the Kin I subfamily of kinesin-related proteins, a unique group of motor proteins that are not motile but instead destabilize microtubules. We show that MCAK is an ATPase that catalytically depolymerizes microtubules by accelerating, 100-fold, the rate of dissociation of tubulin from microtubule ends. MCAK has one high-affinity binding site(More)
Motor proteins in the kinesin-8 family depolymerize microtubules in a length-dependent manner that may be crucial for controlling the length of organelles such as the mitotic spindle. We used single-molecule microscopy to understand the mechanism of length-dependent depolymerization by the budding yeast kinesin-8, Kip3p. We found that after binding at a(More)
BACKGROUND In the cortical region of motile cells, the actin network rapidly reorganizes as required for movement in various directions and for cell-to-substrate adhesion. The analysis of actin network dynamics requires the combination of high-resolution imaging with a specific fluorescent probe that highlights the filamentous actin structures in live(More)
At the leading edge of a motile cell, actin polymerizes in close apposition to the plasma membrane. Here we ask how the machinery for force generation at a leading edge is established de novo after the global depolymerization of actin. The depolymerization is accomplished by latrunculin A, and the reorganization of actin upon removal of the drug is(More)
During mitosis and meiosis, the bipolar spindle facilitates chromosome segregation through microtubule sliding as well as microtubule growth and shrinkage. Kinesin-14, one of the motors involved, causes spindle collapse in the absence of kinesin-5 (Refs 2, 3), participates in spindle assembly and modulates spindle length. However, the molecular mechanisms(More)
In vitro assays that reconstitute the dynamic behavior of microtubules provide insight into the roles of microtubule-associated proteins (MAPs) in regulating the growth, shrinkage, and catastrophe of microtubules. The use of total internal reflection fluorescence microscopy with fluorescently labeled tubulin and MAPs has allowed us to study microtubule(More)
The stepping behavior of single kinesin-1 motor proteins has been studied in great detail. However, in cells, these motors often do not work alone but rather function in small groups when they transport cellular cargo. Until now, the cooperative interactions between motors in such groups were poorly understood. A fundamental question is whether two or more(More)
Kinesin-1 is a motor protein that carries cellular cargo such as membrane-bounded organelles along microtubules (MTs). The homodimeric motor molecule contains two N-terminal motor domains (the motor "heads"), a long coiled-coil domain (the "rod" or "stalk"), and two small globular "tail" domains. Much has been learned about how kinesin's heads step along a(More)
Propagating actin waves are dynamic supramolecular structures formed by the self-assembly of proteins within living cells. They are built from actin filaments together with single-headed myosin, the Arp23 complex, and coronin in a defined three-dimensional order. The function of these waves in structuring the cell cortex is studied on the substrate-attached(More)