Cytoskeletal Flashcards
What makes up tubulin
Alpha and beta
What is considered a basic subunit
alpha and beat dimer
Are microtubules polar
Yes one side is different then the other
What polymerizes microtubules
The subunit
How long is a microtubule
25nm diameter up to 100 micrometer long really long
How many protofilaments in a microtubular
13
It is a perfect tube
No there is seam and they aren’t perfectly lined up
How far is it between and alpha and beta dimer
8 nm
What subunit can bind to Gtp
A binds permantelty to GTP where B can hydrolyze GTP so it can be bound to GTP or GDP
What happens at the protfilament grows
Gtp is hydrolyzed
Which side is negative and which side is positive
The alpha side is negative and the beta is the positive side
How many protofillaments are in singlets doublets and triplets
Singlets have 13 protofilaments
Double and triplets have one tube with 13 protofilaments and one or two 10 protofilament tubes attached
What is found in basal bodies and centrioles
Triplets
What type of microtubules do nerve axons have
Cytoplasmic microtubules that transport things
True or false the cytoplasm of all cells have microtubules
TRUE
What type of microtubules are found in cilia and flagela
Axonemal microtubules
What is MTOC
Micro-tubular organizing center which is where microtubular come from
What is the main MTOC in most cells
The centrosome
What part goes away from the centrsome and what part towards
Negative end goes toward the centrsome where the positive end extends outwards except in a dendrite where it is not continous
What is the centrosome
A major but not only MTOC in animal cells
What do centrosomes contain
Centrioles
Are centrioles in plants
NO
What are centrioles
They are triple microtubules that are stable and tend not to polymerase but they allow for polymerization to occur around them
What allows microtubulars to polymerize in the centrsome
It is filled with pericentriolar matrix that allows them to polymerazie gamma tubulin and augmin
How many triplets are in a ring of a centriole
9
What is the gamm tubulin ring complex
It provides nucleating sites for microtubules it provides a nucleus that can grow
Which way does gamma tubulin help microtubules grow
away from the centrsome
as the negative is sitting in the centrisome with the ring is capped and you can not add anything to the negative end
What does augmin do
Can from a branch to a new microtubular
What end does polymerization occur at
Preferentially at the plus end
When do you have polymerization
When you have an ammount of tubulin that is above critical concentration and a nuclei
What end does it depolymerize faster
The positive end it will depolymerize when you below CC
What happens if you just have monomers
It will take longer because you have to first grow the nuclei
How can you figure out CC
You add monomers and once you reach critical concentration anything above that you will get a filament
What temp do microtubules dissaseemble at
4 degrees
What are microtubules independent of
Cc if there are lots of dimers they will polymerize and head away from the centriole and move to where there is lees concentration adn dimers is de polymerize
What is castrophe
Where depolymerization starts to form it is the peak
What is dissasbley
Depolymerization
What is rescue
When they start polymerizing again
What is oscillations in length is common
Dynamic instability
What does dynamic instability depend on
GTP-B tubulin cap because with the GTP can even protofilaments in the center of tubule are stable
What happens when GTP to GDP hydrolysis reaches the positive end
it weakens the cohesion between protofilaments and fraying occurs
Where does de polymerization occur
The smooth ends fray and it continues towards the positve end
what is tubulin away from the positve end
In the GDP form
What holds the microtubule together
the y gamma on the negative end and the GTP cap on the other end
What does Colchicine do
Depolymerizes
What does Taxol do
Stablize they stay the same size you can use this if you want to see what depolymerization does
What does MAPs do
Alter microtubular stability
What regulates MT spacing
The projection domain can regulate the spacing
What about the binding domains of MAP
They are the same
What is the projection domain of the microtubules for TAU and MAPS
MAP2 has a long projection domain so they are far apary
What are TIPS
The positive end of MT
What is EB1
It is a +TIP that binds to unique structures found on growing(+) end and can stabilize and reduce castrophe
What is TOG domain
The growing protofillaments
What is XMAP215 and CLASP
They can bind to TOG and stabilize protofilaments to prevent catastrophe
What is kinesin-13
Regulated by ATP removes terminal dimers causes de pol at end doesnt matter the CC if you have enough it will de pol
What is Stathmin
Binds to tubulin dimers in the curve may promote GTP hydrolysis
What is stathmin inactivated by
Phosphorylation
