Walking Heads: Kinesin or The Little Engine That Could 🙂
Have you wondered how things (like vesicles and mitochondria) move about inside a cell? They don’t just drift aimlessly through the thick cytoplasmic soup-rather they are ferried by kinesin, a hard working molecular motor.
To watch mitochondria motor down an invisible highway inside a nerve cell see: Mitochondrial Moving in an Axon.mov
The kinesin highway is made of microtubules : a bundle of 13 filaments that have distinct ends (known as + and – ends). Kinesins move cargo towards the + end (from the center of the cell to the periphery) and dyneins move them in the opposite direction. Watch what happens when fluorescent microtubules are placed on a slide coated with kinesin! Kinesin-1 gliding motility assay, whole casein passivation.avi
Cargo is tethered to kinesin by a long coil. The two heads of the motor walk along the microtubule in a hand-over-hand mechanism using ATP hydrolysis as a power source. Each ATP moves the motor one 8 nanometer step. Notice that kinesin is a processive motor: once it is attached to the microtubule it takes (on average)100 steps, before it lets go.
For a narrated 2 min mechanism see:Kinesin Walking Narrated Version for Garland
Many, many thanks to Kevin Staff for being such a sport and converting the kinesin video into an animated gif! Special shout out to Andreas Schou who requested some ‘kinesin love’ and to Henry K.O. Norman who is working on an animated production on cellular mechanisms.
For #ScienceSunday curated by Allison Sekuler and Robby Bowles .