Biophysicists at Stanford University have finally answered one of the most fundamental questions in molecular biology: How does the tiny motor molecule, known as kinesin, move across a living cell? According to the researchers, the solution to this longstanding problem will provide new insight into how motor proteins function, and may open new avenues of investigation for the treatment of cancer and various neurodegenerative diseases, such as Alzheimer's and Huntington's.

The study, published in the Dec. 4 online edition of the journal Science, was co-authored by Steven M. Block, a professor of applied physics and of biological sciences at Stanford.

"Motion at the cellular level is a hallmark of being alive," Block said. "A fundamental question is, how did living organisms figure out how to move? The answer is they developed kinesin and several other very efficient protein motors. If kinesin were to fail altogether, you wouldn't even make it to the embryo stage, because your cells wouldn't survive. It's that important."

Discovered in 1984, kinesin is now recognized as the workhorse of the cell, hauling chromosomes, neurotransmitters and other vital cargo along tiny molecular tracks called "microtubules." Many types of kinesin and kinesin-related proteins have been discovered in the past two decades in a wide range of organisms from yeast to humans.

"Kinesin functions like a locomotive in cells to ferry cargo back and forth," Block said. "In brain cells, for example, it grabs these tiny sacs called vesicles, which are loaded with neurotransmitters that are needed for neurons to function, and moves them very long distances along microtubules."

A mere three-millionths of an inch long, a typical kinesin molecule has a tail on one end that hauls the cargo and two globular heads on the other end that alternately grab the microtubule and pull the cargo forward. One head has to be attached to the microtubule at all times for kinesin to adv
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Contact: Mark Shwartz
mshwartz@stanford.edu
650-723-9296
Stanford University
5-Dec-2003

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