(dramatic music) - Just like a busy city, there's constant motion
inside of your cells. There's new construction, demolition, and, most importantly, transporting goods from one place in the cell to another. Cells transport goods
along cellular roadways. To transport cargo along these routes, the cells use motor proteins. Kinesin is one of these motor proteins. If you didn't have kinesin
and other motor proteins, you simply wouldn't be alive. All the cells in your body depend upon these tiny motor proteins to
organize and power themselves, to divide and multiply and to
communicate with other cells. Let's start with how you
began as a fertilized egg. That egg has to divide
into many more cells. All of those divisions require kinesin and many other motor proteins. Development, forming tissues
in different parts of your body requires molecular motion
and motor proteins. Every cell of your body
requires them for survival. What we know now is that kinesin
effectively has two legs, and these legs are able to coordinate a walking motion along a track. That track is called a microtubule. And the kinesin undergoes this beautiful choreographed walking action. While the kinesin is
walking along this track, at the other end of the kinesin, it gets hooked up to a cargo. These motor proteins move
quickly and efficiently. Relative to their size, they move as fast as a car on a freeway, but they're four times more efficient than your car in converting
chemical energy into motion. We discovered kinesin in 1984. I was 25 years old at the
time and a graduate student. I was interested in the
transportation system inside of nerve cells, and what makes
nerve cells so interesting is that they're
extraordinarily long cells. For example, the part of your nerve cell that has the nucleus, where the DNA is, is located in your spinal cord. But, it can extend a very long tube all the way, for example, to your foot. All of the building blocks for that nerve cell are made in your spinal cord, and all those building
blocks have to be shipped to the very end of that
nerve cell a meter away. There had to be some
kind of transport system that was moving these building
blocks inside the nerve cell and I wanted to know how that
transportation system worked. After we got this transport
to work in this test tube, the hunt was on then to
find the key molecule that was responsible for that movement. And, we eventually found it, and it turned out to be
something completely new that no one had ever discovered before. Watching these movements
under the microscope, it was fascinating, then, to figure out how does this motor actually work? How does something that's
a millionth of an inch in size generate that motion? My lab at UCSF spent about 10 to 20 years trying to figure out the
answer to that question. We know about kinesin now,
we a lot about how it moves, but there's still so many
fundamental questions that we don't know about how
all this motility is regulated, how all of these cargoes know
how to go to the right places. There are always new questions that one wants to know the answers to.
