Lecture 9 - microtubules and actin filaments Flashcards
what are microtubule subunits
tubulin heterodimers
theyre made up of one alpha and one beta tubulin
diff between plus and minus ends in MT
plus = grow fast
also shrink at this end
minus = very little if any movement
what element necassary to form micotubules in a test tube
Mg2+
why cant tubulin polymerise spontaneously
too little concentration
what is used to speed up tubulin polymerisation
gamma-tubulin and other proteins
process is called nucleation
it gives it a surface to attach to and polymerise from there
in basal bodies what do MT form
bundles of MT form in the cillia
what are MT embedded in
centrosome
what is dynhamic instability
MT switch between growing and shrinking, and this happens independently of other MT
are MT GTPase or ATPases
GTPase
which form of tubulin can polymerise
GTP tubulin
and remember GTP hydrolysis to GDP is slow
why will MT start to shrink if GTP cap is gone
GTP tubulin bind tighter to each other than GDP, so structure is less stable without the cap
starts to unravel and shrink
which protein marks GROWING microtubules and how
EB1
binds inly to GTP bound tubulin
what is catastophe
when GTP cap is lost
then MT will depolymerise
whats it called when GTP cap reforms and MT starts regrowing
rescue !
what natural thing stabilises MT
microtubule asssociated proteins
MAPs
