NEARLY 50 YEARS after the discovery of the walking molecular motor dynein, researchers have finally solved the first X-ray crystal structure of its massive motor domain. The milestone will permit researchers to tweak and tune the molecular engine that drives the transport of neurotransmitter vesicles, mRNA, and nuclei around biological cells and powers the beating of flagella and cilia. Seven years after he first took a stab at solving dynein’s crystal structure as a postdoc, Andrew P. Carter, now a structural biologist at the Medical Research Council, in Cambridge, England., and Carol Cho, a graduate student in Ronald D. Vale’s cell biology lab at the University of California, San Francisco, finally elucidated the protein motor at 6-A resolution ( Science , DOI: 10.1126/science.1202393). “This is a major breakthrough,” comments Stan Burgess, a biologist at Leeds University, in England, who publishes electron microscopy images of molecular motors. “Even though it is still not yet atomic resolution, the ...