User:Andy Maloney/Notebook/Lab Notebook of Andy Maloney/2009/08/27/Kinesin walking

From OpenWetWare
Jump to navigationJump to search

Today Larry and I decided to go over some simple kinesin stepping ideas. I'm still far behind him when it comes to the literature so I need to catch up at some point.

I am going to basically rehash what he has done already in my own words. This is to benefit me and no one else.

Error creating thumbnail: File missing

The picture above describes what people think is going on when a kinesin molecule walks along a microtubule. Basically what is happening is:

[math]\displaystyle{ \begin{align} K_1\cdot ATP\cdot MT+K_2\cdot ADP&\leftrightharpoons K_1\cdot ATP\cdot MT+K_2\cdot ADP\cdot MT\\ K_1\cdot ATP\cdot MT+K_2\cdot MT &\leftrightharpoons K_1\cdot ADP\cdot MT\cdot P_i+K_2\cdot MT\\ K_1\cdot ADP\cdot MT+K_2\cdot MT+P_i&\leftrightharpoons K_1\cdot ADP+K_2\cdot MT\\ &\leftrightharpoons K_1\cdot ADP+K_2\cdot ATP\cdot MT \end{align} }[/math]

And then it repeats the process. Of course each reaction has associated rate constants to them and we do know some of them. Not only do the 7 steps mentioned above occur but, more "non regular" steps can occur (for each step) that can either slow down the process or inevitably stop the processivity.

Constraints

Larry and I also hashed out some constraints that think kinesin may have. They include:

  • When a foot has an ATP bound to it, this configuration has a stronger binding to the microtubule than a foot that has an ADP bound to it.
  • If a kinesin is not bound to a microtubule, then it more than likely has an ADP bound to it.
  • There is a very low chance that ATP will be bound to both feet.
  • Block states that the kinesin foot spends 93% of its time unbound to the microtubule if it is under a load.
  • 1:1 ratio of ATP used for each step.
  • A kinesin molecule takes approximately 100 steps before detaching from a microtubule.
  • Kinesin's travel time is about 1 second.
  • The kinesin's velocity follows Michaelis-Menten kinetics.

Things to look up

We also came up with a slew of things to look up. Each one encompasses an idea that we have about the way kinesin walks.

  • Is there a difference in the crystal structure of a kinesin foot when it has ATP or ADP bound?
  • How do microtubule residues interact with kinesin's feet?
  • How ATP and the "power stroke" are related.
  • Does ATP interact with the residues on microtubules? If so, how.
  • Is strain real? I.e. the strain felt in kinesin's legs.
  • What is the persistence length for the legs of kinesin?
Retrieved from "https://openwetware.org/mediawiki/index.php?title=User:Andy_Maloney/Notebook/Lab_Notebook_of_Andy_Maloney/2009/08/27/Kinesin_walking&oldid=442300"