PITTSBURGHThe transport system inside living cells is a well-oiled machine with tiny protein motors hauling chromosomes, neurotransmitters and other vital cargo around the cell. These molecular motors are responsible for a variety of critical transport jobs, but they are not always on the go. They can put themselves into "energy save mode" to conserve cellular fuel and, as a consequence, control what gets moved around the cell, and when.
A new study from Carnegie Mellon University and the Beatson Institute for Cancer Research published in the Aug. 12 issue of Science describes how the motors fold in on themselves, or save energy, when their transport services aren't required. According to the researchers, the solution to this molecular puzzle provides new insight into how molecular motor proteins are regulated, and may open new avenues for the treatment of various neurodegenerative diseases, such as Alzheimer's and Huntington's.
"Molecular motor proteins play a major role in all eukaryotic cells, but they are particularly critical to nerve cells," said David Hackney, professor of biological sciences in the Mellon College of Science, and one of the paper's authors. "Nerve cells have this special problem where proteins, such as receptors for neurotransmitters, get synthesized in the cell body and have to be shipped all the way down the axon. Problems in this transport system may play a role in a number of neurological conditions."
Hackney focuses his research on kinesin-1, the principle motor protein that moves cargo from the nerve cell body down the axon. A typical kinesin molecule has two tails on one end that attach to the cargo and two globular heads on the other end that crank along fibers inside the cell called microtubules, pulling the cargo forward. The movement of the heads, or motor domains, is fueled by the breakdown of ATP, a molecule that stores the energy that drives cellular work. When cargo isn't attached, ki
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Carnegie Mellon University