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=== Axonemal dyneins  ===
=== Axonemal dyneins  ===


Axonemal dynein includes heterodimers, two motor-domain heads, and heterotrimers, three motor-domain heads <ref>Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular Biology of the cell, fifth edition, New York: Garland Science.</ref>. These are highly specialised for sliding movements of microtubules that drive the beating of [[Cilia|cilia]] and [[Flagella|flagella]] <ref>Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular Biology of the cell, fifth edition, New York: Garland Science.</ref>. In a test tube axonemal dyneins can move microtubules at a rate of 14µm/sec <ref>Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular Biology of the cell, fifth edition, New York: Garland Science.</ref>. This is far faster than kinesins which are only able to move at speeds of around 2-3µm/sec <ref>Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular Biology of the cell, fifth edition, New York: Garland Science.</ref>.&nbsp;  
Axonemal dyneins are found in the [[Axoneme|axoneme]] of the cellular appendages of cilia and flagella and using ATP, cause the rhythmic, beating movement of these structures through the mechanical action of sliding up and down the microtubules within the axonemal cytoskeletal core<ref>Wikipedia. Dynein. 2017. Cited [05.12.2017] Available from: https://en.wikipedia.org/wiki/Dynein</ref>. Axonemal dynein includes heterodimers that have two different motor-domain heads, and heterotrimers that have three different motor-domain heads <ref>Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular Biology of the cell, fifth edition, New York: Garland Science.</ref>. &nbsp;In a test tube axonemal dyneins can move microtubules at a rate of 14µm/sec <ref>Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular Biology of the cell, fifth edition, New York: Garland Science.</ref>. This is far faster than kinesins which are only able to move at speeds of around 2-3µm/sec <ref>Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular Biology of the cell, fifth edition, New York: Garland Science.</ref>.&nbsp;  


=== References  ===
=== References  ===


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Revision as of 15:55, 5 December 2017

There are two types of microtubule motor proteins these are kinesins and dyneins. They have globular heads which bind to the microtubule and also bind ATP. The hydrolysis of ATP is what drives movement. The tail regions of the motor proteins bind the cargo e.g. endoplasmic reticulum, Golgi apparatus. The dyneins are a family of minus-end-directed microtubule motors, whereas kinesins are plus-end-directed motors [1]. Dyneins are composed of two or three heavy chains and a large variable number of associated intermediate and light chains [2]. The dyneins family consists of two major branches, cytoplasmic dynein and axonemal dynein [3].

Cytoplasmic Dynein

Cytoplasmic dynein is typically composed of heavy chain homodimers, with two large motor domains as heads [4]. These are found in probably all eukaryotic cells as they are important for vesicle trafficking and for the localization of the Golgi apparatus near to the centre of the cell [5]. Cytoplasmic dynein has molecular mass of about 1.5 Megadaltons [6]. Cytoplasmic dynein transports its cargo by “walking” along the microtubule without becoming detached [7].

Axonemal dyneins

Axonemal dyneins are found in the axoneme of the cellular appendages of cilia and flagella and using ATP, cause the rhythmic, beating movement of these structures through the mechanical action of sliding up and down the microtubules within the axonemal cytoskeletal core[8]. Axonemal dynein includes heterodimers that have two different motor-domain heads, and heterotrimers that have three different motor-domain heads [9].  In a test tube axonemal dyneins can move microtubules at a rate of 14µm/sec [10]. This is far faster than kinesins which are only able to move at speeds of around 2-3µm/sec [11]. 

References

  1. ↑ Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular Biology of the cell, fifth edition, New York: Garland Science.
  2. ↑ Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular Biology of the cell, fifth edition, New York: Garland Science.
  3. ↑ Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular Biology of the cell, fifth edition, New York: Garland Science.
  4. ↑ Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular Biology of the cell, fifth edition, New York: Garland Science.
  5. ↑ Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular Biology of the cell, fifth edition, New York: Garland Science.
  6. ↑ Wikipedia (2011) Dynein [Online] Available at: http://en.wikipedia.org/wiki/Dynein ( last accessed 28.11.2011).
  7. ↑ Wikipedia (2011) Dynein [Online] Available at: http://en.wikipedia.org/wiki/Dynein ( last accessed 28.11.2011).
  8. ↑ Wikipedia. Dynein. 2017. Cited [05.12.2017] Available from: https://en.wikipedia.org/wiki/Dynein
  9. ↑ Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular Biology of the cell, fifth edition, New York: Garland Science.
  10. ↑ Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular Biology of the cell, fifth edition, New York: Garland Science.
  11. ↑ Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K. and Walter, P. (2008) Molecular Biology of the cell, fifth edition, New York: Garland Science.


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