Using the following figure below as an example, draw a dynamic stability graph f

Question

Using the following figure below as an example, draw a dynamic stability graph for MT (microtubule formation) as the following experiment is done (you are plotting length change vs minutes – just focus on overall length change of a MT – don’t worry about plus vs minus end).  Assume the effect of the drugs or proteins only last for a 5-minute time interval and there is always GTP-tubulin. In addition to your graph, explain with a few words, what is happening (why the graph is going up, down, or staying flat).

A) At time 0 there is abundant GTP-tubulin

B) At 5 minutes, katanin is added

C) At 10 minutes, MAPS are added

D) At 15 minutes, stathmin/Op18 is added

E) At 20 minutes, catastrophins are added

F) What could you add next to stop the depolymerization and promote rescue?

GTP cap GTP tubulin added HIGH GTP-tubulin GTP hydsolzed, GTP cap depleted GTP tubuin CATASTROPHE al Model forhow the GTP cap function GROWTH GTP tubuin addedGTP hydrolyzed, MT Gowth sesumes CATASTROPHE O RESQUE de Plus end Minus end 15 30 45 Minutes b) Evidence for dynamic instabilty Figure 13-7 The GTP Cap and Its Role in the Dynamic M) Oysvc Instability of Microtu bules. (al When the tubulin cancen tration is atabláty of high, GTP ubulin is added to the micro tubule tip faster than the in- oarparated GTP canbe hydraly and. The resting GTP cap stabilizes he MT tipand pramates further growth. At lawer tubulin cancen tra ions, the rate of growth dece ases,thereby alawing GTP hydrdlysis catch up. This creates an unstable tip {no GTP capo tatvars MT depolymerizatan (b) in an indvidual MT abserved by light mao oopy growth and catasraphic shrink age can ooour. Plus and minus ends grow and shink independently; changes in length are much mone dynamic at fhe plus and 0 Re soue invalves the switd ram shinkage ta growth

Explanation / Answer

A) acoording to the given graph, at time 0 = there is abundant GTP-tubulin and MT grow in length.

B) At 5 minute = ketanin is added. Ketanin is a microtubule severing protein wich breaks microtubules thus, leads to reduction in MT length .

C) At time 10 minute = MAPS are added . Microtubule assisted protein(MAPS) isknown to stablize the microtubules thus promote assemble and leads to MT grow in length.

D) At time 15 minute = stathmin/Op18 is added. Stathmin/Op18 is a microtubule destablizing protein, binds to tubulin dimer and inhibits polymerization thus leads to reduction of MT length.

E) At time 20 minute= catastrophins added. Catastrophins are known to drastricaly depolymrize (rapidly shorting state ) the MT and increases the frequency of catastroph.

F) Cytoplasmic linker proteins (CLP) promotes rescue and cause sudden sieze in the catastroph of MT and thus restore the MT length.

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