Microtubule section 1 Flashcards
Both actin and microtubules frequently disassemble and reassemble as the result of a stimulus
Intermediate filaments don’t do so as much
Why is it better for proteins to form multimeric filaments?
The multimer is thermodynamically stable, won’t just break apart. It will also assemble a bond at a time at the end instead of breaking multiple bonds
What are microtubules made out of?
Tubulin
What is the difference between alpha and beta tubulin?
beta tubulin can hydrolyze GTP. The Beta end is positive. The microtubule is built towards the plus end of the microtubule.
How does the microtubule resist being hydrolyzed?
It forms an ATP cap on actin and a GTP cap on Microtubules
How does a GTP cap on the plus end stabilize microtubules?
It straightens the microtubule and it forms stronger lateral bonding
which subunit is the GTP cap binding too? is it capable of binding to all of this subunit?
The beta subunit. Yes GTP GDP binding is seen for ALL Beta subunits
Does the GTP cap bind to all beta subunits?
All those at the top/plus end of the protein. Maybe the top 15 for each column
When GTP is bound to beta subunit? GDP?
straight stable
curved unstable
How much faster does microtubule depolymerization occur if the microtubule has a GDP cap vs a GTP cap?
the microtubule breaks down 100x faster
What does dynamic instability refer to?
How microtubules switch from periods of slow growth to rapidly shrinking
Which end of a microtubule grows faster?
The plus end
What is treadmilling (in microtubules)?
When the plus end grows at roughly the rate that the minus end shrinks
What causes dynamic instability?
Loss and recovery of GTP cap.
each MT grows and shrinks _____ of other MTs.
independently
Catastrophe refers to?
The rapid loss of alpha and beta tubulin which occurs in the absence of the GTP cap.
Rescue refers to?
When a microtubule in catastrophe regains its GTP cap and starts growing again.
Taxol come from where
The Pacific Yew
The drug produced from taxol is called
Paclitaxel
The mechanism by which taxol affects cancer is?
polymerizes microtubules
Colchicine comes from where?
The Coleus plant
The mechanism by which colchicine acts is?
It depolarizes microtubules.
The drug produced from colchicine is called
Oryzalin, it is a herbacide
What is the difference between gamma tubulin and and gamma turc?
gamma tubulin is a modified form of tubulin protein. It is found on the edge of gamma TuRC complex which attaches to the end of the alpha tubulin. It looks like a lock washer
Where are gamma TuRC complexes generally found.
in the pericentriolar material (next to the centrioles).
Which side of the tubulin attaches to the gamma turc complex
Alpha/negative
What is the structure of a centriole?
9-3 structure, inner microtubule is complete
Distal appendages occur only on…
The mother centriole
How many SAS-6 dimers are within a centriole?
9, one for each of the 9-3 microtubules
