BIOC3390 Tutorials: 16 & 18 November 1999

Dynein in tracheal epithelial cells

There are two kinds of dynein: the protein found in cilia differs slightly from the cytosolic version responsible for some types of axonal transport.

Vitually all eukaryotic cilia and flagella have the same basic organisation, based on the 9+2 arrangement of microtubules illustrated in the diagram. The two inner microtubules are singlet structures, but the outer ring consists of 9 doublet microtubules, each bearing hundreds of dynein molecules distributed along their length.

The individual doublet microtubules are cross-linked by nexin and connected to the central structure by radial spokes. Consequently, when the dynein molecules in one doublet exert a force on the neighbouring doublet, the whole structure bends instead of the microtubules sliding against each other. This also requires that the activity of individual dynein molecules is regulated in some way.

Dynein molecules towards the outside of the cilium/flagellum have three functional head groups, but those on the inside have only two.


In addition to the bending motility of the axonemes, there are separate anterograde and retrograde transport systems inside each flagellum to assemble and replace the protein components, and a third system responsible for surface motility on the plasmalemma surrounding the organelle. One of the dynein light chains is essential for the retrograde transport system.

For an introduction to pulmonary function, consult one of the physiology texts in the medical library, or visit the Cornell Medical Center website. [First click the courseware icon, then go to pathology notes, then go to respiratory. Click on the coloured icons to inspect individual histology slides.] Tracheal cilia beat about 20 times per second, and the activities of adjacent cells are synchronised by travelling calcium waves. Shovelling mucus is hard work, but it is essential for normal life. Patients with Kartagener syndrome have defective dynein arms and suffer from chronic respiratory disease, immotile sperm and left/right inversion of the viscera. Visit OMIM and compare Kartagener syndrome with cystic fibrosis, where the mucus is too stodgy. See also:

Asai, DJ (1996) Functional and molecular diversity of dynein heavy chains. Seminars in Cell & Developmental Biology 7(3), 311-320. [Click HERE for the full-text PDF file.]

Cosson, J (1996) A moving image of flagella: news and views on the mechanisms involved in axonemal beating. Cell Biology International 20(2), 83-94 [Strongly recommended. Click HERE for the abstract, or HERE for a full-text PDF file.]

Fang, YI et al (1997) Purealin Blocks the Sliding Movement of Sea Urchin Flagellar Axonemes by Selective Inhibition of Half the ATPase Activity of Axonemal Dyneins Biochemistry 36(50), 15561-7. [Click HERE for HTML format, or HERE for the PDF version.]

Gee, MA et al (1997) Nature 390(6660), 636-9. [Write down the volume and page numbers for future reference. Click HERE for access instructions. Click HERE to gain access via the Leeds University network.]

Holleran, EA et al (1998) The role of the dynactin complex in intracellular motility. International Review of Cytology 182, 69-109. [No electronic copies are available.]

Hunt, AJ (1998) Molecular motors - Keeping the beat. Nature 393(6686), 624-625. [See also the article by Shingyoji et al below. Write down the volume and page numbers for future reference. Click HERE for access instructions. Click HERE to gain access via the Leeds University network.]

Orozco, JT et al (1999) Movement of motor and cargo along cilia. Nature 398(6729), 674. [Write down the volume and page numbers for future reference. Click HERE for access instructions. Click HERE to gain access via the Leeds University network.]

Pazour, GJ et al (1998) A Dynein Light Chain Is Essential for the Retrograde Particle Movement of Intraflagellar Transport (IFT). J. Cell Biol. 141(4), 979-92. [Click HERE for HTML format, or HERE for the PDF version.]

Sakakibara, H et al (1999) Inner-arm dynein c of Chlamydomonas flagella is a single-headed processive motor. Nature 400(6744), 586-590. [Write down the volume and page numbers for future reference. Click HERE for access instructions. Click HERE to gain access via the Leeds University network.]

Samso, M et al (1998) Structural Characterization of a Dynein Motor Domain. J. Mol. Biol. 276(5), 927-37. [Click HERE for HTML format, or HERE for the PDF version.]

Schroer, TA (1996) Structure and function of dynactin. Seminars in Cell & Developmental Biology 7(3), 321-328. [Click HERE for the full-text PDF file.]

Shingyoji, C et al (1998) Dynein arms are oscillating force generators. Nature 393(6686), 711-714. [See also the article by Hunt above on page 624. Write down the volume and page numbers for future reference. Click HERE for access instructions. Click HERE to gain access via the Leeds University network.]

Tai, AW et al (1999) Rhodopsin's carboxy-terminal cytoplasmic tail acts as a membrane receptor for cytoplasmic dynein by binding to the dynein light chain Tctex-1. Cell 97(7), 877-887. [No electronic copies are available.]

Yamada, A et al (1998) Unidirectional movement of fluorescent microtubules on rows of dynein arms of disintegrated axonemes. J. Cell Science 111(1), 93-98. [Click HERE for the abstract, or HERE for the PDF version.]

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