title: A Structural Basis for How Motile Cilia Beat.
abstract: The motile cilium is a mechanical wonder, a cellular nanomachine that produces a high-speed beat based on a cycle of bends that move along an axoneme made of 9+2 microtubules. The molecular motors, dyneins, power the ciliary beat. The dyneins are compacted into inner and outer dynein arms, whose activity is highly regulated to produce microtubule sliding and axonemal bending. The switch point hypothesis was developed long ago to account for how sliding in the presence of axonemal radial spoke-central pair interactions causes the ciliary beat. Since then, a new genetic, biochemical, and structural complexity has been discovered, in part, with Chlamydomonas mutants, with high-speed, high-resolution analysis of movement and with cryoelectron tomography. We stand poised on the brink of new discoveries relating to the molecular control of motility that extend and refine our understanding of the basic events underlying the switching of arm activity and of bend formation and propagation.
authors.affiliation: Peter Satir ( peter.satir@einstein.yu.edu ) is affiliated with the Department of Anatomy and Structural Biology at Albert Einstein College of Medicine, in New York, New York. Thomas Heuser is affiliated with the Electron Microscopy Facility, in the Campus Science Support Facilities of the Campus Vienna Biocenter, in Vienna, Austria. Winfield S. Sale is affiliated with the Department of Cell Biology at Emory University, in Atlanta, Georgia.
authors.forename: Peter
authors.initials: P
authors.lastname: Satir
authors.affiliation: Peter Satir ( peter.satir@einstein.yu.edu ) is affiliated with the Department of Anatomy and Structural Biology at Albert Einstein College of Medicine, in New York, New York. Thomas Heuser is affiliated with the Electron Microscopy Facility, in the Campus Science Support Facilities of the Campus Vienna Biocenter, in Vienna, Austria. Winfield S. Sale is affiliated with the Department of Cell Biology at Emory University, in Atlanta, Georgia.
authors.forename: Thomas
authors.initials: T
authors.lastname: Heuser
authors.affiliation: Peter Satir ( peter.satir@einstein.yu.edu ) is affiliated with the Department of Anatomy and Structural Biology at Albert Einstein College of Medicine, in New York, New York. Thomas Heuser is affiliated with the Electron Microscopy Facility, in the Campus Science Support Facilities of the Campus Vienna Biocenter, in Vienna, Austria. Winfield S. Sale is affiliated with the Department of Cell Biology at Emory University, in Atlanta, Georgia.
authors.forename: Winfield S
authors.initials: WS
authors.lastname: Sale
keywords: axoneme; cilia; dynein; eukaryotic flagella; microtubules; motility