Scientists Discover New Molecular Motor 'Clutch'  How would a
vehicle slow or stop on time or on target without some mechanism
to disengage the engine from the drive train?  The vehicles that
transport items within living cells face the same challenges as
vehicles that transport people and goods. One molecular vehicle
inside cells uses a protein motor called dynein. And researchers
just discovered that a detachable clutch-like protein regulates
its speed.1  The dynein motor walks along microtubules, which
are like train tracks inside cells. One end of the two-motor
complex, which is a complex of 12 separately manufactured
protein parts, has a long stem that acts like a trailer hitch
attachable to a cargo bundle. At the other end, a short stalk
connects to a pair of molecular leg-like appendages that
alternately attach and detach as they literally walk down the
length of a microtubule. This way, a cell transports products
from one area to another. But what if there was no way to
control how fast the dynein wal