UMMS Affiliation

Department of Radiology, Division of Cell Biology and Imaging; Witman Lab

Publication Date


Document Type



Cell Biology | Cellular and Molecular Physiology | Molecular Biology | Radiology


Motility of cilia/flagella is generated by a coordinated activity of thousands of dyneins. Inner dynein arms (IDAs) are particularly important for the formation of ciliary/flagellar waveforms, but the molecular mechanism of IDA regulation is poorly understood. Here, we show using cryo-electron tomography and biochemical analyses of Chlamydomonas flagella that a conserved protein FAP44 forms a complex that tethers IDA f (I1 dynein) head domains to the A-tubule of the axonemal outer doublet microtubule. In wild-type flagella, IDA f showed little nucleotide-dependent movement except for a tilt in the fbeta head perpendicular to the microtubule-sliding direction. In the absence of the tether complex, however, addition of ATP and vanadate caused a large conformational change in the IDA f head domains, suggesting that the movement of IDA f is mechanically restricted by the tether complex. Motility defects in flagella missing the tether demonstrates the importance of the IDA f-tether interaction in the regulation of ciliary/flagellar beating.

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© 2018 Kubo et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (

DOI of Published Version



Mol Biol Cell. 2018 May 1;29(9):1060-1074. doi: 10.1091/mbc.E17-11-0689. Epub 2018 Apr 9. Link to article on publisher's site

Journal/Book/Conference Title

Molecular biology of the cell

Related Resources

Link to Article in PubMed

PubMed ID


Creative Commons License

Creative Commons Attribution-Noncommercial-Share Alike 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 License.