Why Kinesin is Better Than Those Other Proteins?

Kinesin's Main Purpose
     
       Kinesin is an amazing protein! It transports molecules and organelles throughout the cell by walking (that's right walking?!?!) across microtubules within the cell. Did you think everything in the cell just knew where to go on it's own? No way! Without kinesin, organelles (including peroxisomes, mitochondria, and lysosomes) and vesicles wouldn't be transported to their proper locations when they tried to work their way through the cytoplasm. They'd be lost and the cell wouldn't be able to function properly. That's kind of a problem. Lucky for you, the cells do have kinesin!

Other Functions of Kinesin

        Kinesin doesn't just function in transporting organelles and molecules throughout the cell though. Ohhhh no. It also helps in the process of mitosis. Kinesin anchors itself to the chromosomes and connects them to the microtubules made by the spindles. These kinesin proteins then move down the microtubules and start to pull them apart. Kinesin is what allows the chromosomes to split huh? I wonder if we would be able to create new cells without kinesin then? Probably not. Just another reason kinesin is pretty awesome. 

        

      Now that we know the awesome things kinesin does, look at it's awesome symmetry! It has two motor motor domains and a tail.  The motor domains are the "feet" that move across the microtubule. The tail is what totes along the molecule or organelle that needs to get moved around the cell, through the cytoplasm. The structure of kinesin is simple, but efficient. What more could you ask for?

         Here's a video of kinesin doing it's thing! Isn't it awesome?? (I know you're stubborn, but admit it. It's pretty stinkin' cool.) : 

After watching this video and thinking about its importance to the cell, it's hard to dispute that kinesin isn't one cool protein. Kinesin helps make sure things in the cell get where they need to go, and it does so in an interesting way. This is why kinesin is better than those other proteins. 

Sources:

http://www.rcsb.org/pdb/files/3kin.pdb

http://www.mpasmb-hamburg.mpg.de/mand-pdf/Mandelkow_Mandelkow_2002_TCB.pdf

http://www.cellbio.duke.edu/kinesin/MTdisassembly.html

http://www.cellbio.duke.edu/kinesin/KinesinFunctionLinks.html

For Video:

http://www.youtube.com/watch?v=y-uuk4Pr2i8

Structural image made on pymol with PDB file:

http://www.rcsb.org/pdb/files/3kin.pdb 

Sequence: >3KIN:A|PDBID|CHAIN|SEQUENCE

ADPAECSIKVMCRFRPLNEAEILRGDKFIPKFKGEETVVIGQGKPYVFDRVLPPNTTQEQVYNACAKQIVKDVLEGYNGT
IFAYGQTSSGKTHTMEGKLHDPQLMGIIPRIAHDIFDHIYSMDENLEFHIKVSYFEIYLDKIRDLLDVSKTNLAVHEDKN
RVPYVKGCTERFVSSPEEVMDVIDEGKANRHVAVTNMNEHSSRSHSIFLINIKQENVETEKKLSGKLYLVDLAGSEKV
>3KIN:B|PDBID|CHAIN|SEQUENCE
NKSLSALGNVISALAEGTKTHVPYRDSKMTRILQDSLGGNCRTTIVICCSPSVFNEAETKSTLMFGQRAKTIKNTVSVNL
ELTAEEWKKKYEKEKEKNKALKSVIQHLEVELNRWRN
>3KIN:C|PDBID|CHAIN|SEQUENCE
ADPAECSIKVMCRFRPLNEAEILRGDKFIPKFKGEETVVIGQGKPYVFDRVLPPNTTQEQVYNACAKQIVKDVLEGYNGT
IFAYGQTSSGKTHTMEGKLHDPQLMGIIPRIAHDIFDHIYSMDENLEFHIKVSYFEIYLDKIRDLLDVSKTNLAVHEDKN
RVPYVKGCTERFVSSPEEVMDVIDEGKANRHVAVTNMNEHSSRSHSIFLINIKQENVETEKKLSGKLYLVDLAGSEKV
>3KIN:D|PDBID|CHAIN|SEQUENCE
NKSLSALGNVISALAEGTKTHVPYRDSKMTRILQDSLGGNCRTTIVICCSPSVFNEAETKSTLMFGQRAKTIKNTVSVNL
ELTAEEWKKKYEKEKEKNKALKSVIQHLEVELNRWRN

Background about Kinesin

     Kinesin is a motor protein that travels along microtubules in the cell. These motor proteins transport various different molecules and organelles to different locations in the cell. According to Schnitzer's paper, kinesin takes "steps" on a microtubule of approximately 8 nm. Each one of these steps, without an organelle or molecule anchored to kinesin, takes one ATP to give it enough energy to move. Kinesin hyrdolyzes the ATP so it reaches its activation energy and step forward. Mandekow speaks about how kinesin has been found to function in mitosis by moving the microtubules from the spindle into place. Kinesin also anchors to the chromosomes to pull them apart across the microtubules.

The main location in its structure that is important is its motor domain where the ATP is hydrolyzed. As stated before, this gives the kinesin the energy to take a "step" down a microtubule. Two motor domains are present on each kinesin. These domains are what look like the "feet" in this animation:

Kinesin is believed to possibly have some applications with Alzheimer's disease and a disease  referred to as Charcot-Marie-Tooth type 2A. While the correlation is small in these diseases, these diseases work with a chain in kinesin that transport molecules through the cell.

Kinesin has also been found to not only move across microtubules, but to break them apart as well. The kinesin breaks the microtubules formed during mitosis. It attaches to the ends of microtubule and then begins to depolymerize the microtubule. (Kinesin Disassembly)




Kinesin hydrolyses one ATP per 8-nm step (Schnitzer)

Kinesin and Disease (Mandelkow)

Kinesin Disassembly

General Functions of Kinesin

Here are a few images of my protein, Kinesin! Kinesin is a motor protein that "walks" across microtubules in the cell.

Cartoon model:

Sphere model (grey is carbon):

String model:

 Surface model:

Mesh model: