Microtubule Functions Flashcards
What way is vesicle transport
Bi-directional
What do the heavy chains have
Head are flexible and neck (linker) and stalk they have atpase activity and MT binding ability
What do light chains recognize
They recognize and bind to the cargo
how many bands would you see in an ordinary kinase
3 because the heavy vhains are the same size and two light chains
What does Kinesin 1do
Kinesin one is found in the cytoplasma it has 2 heavy chains and 2 light chains but shows three bands
What does kinesin 2 do
3 different kinesin protiens (heterotrimeric) 2 different heavy chains and one light chain so nothing is the same
What does kinesin 5 do
It is biopolar so both sides are the same 2 parts of heavy chains they do not bind to cargo there are 4 heavy chains in total and 2 head domains that help with sliding only one band
What does Kinesin 13 do
A motor protien that had depolymerization ATP hydrolyze removes dimers 2 head domain and neck domain not really moving to plus end they are from both ends
What is the typical movement
Usually anterograde
What does ATP hydrolysis do in kinesin
Causes conformational changes in kinesin
When ATP is hydrolyzed how much does each head moved
16nm each foot takes 8nm so the total is 16 nm
How is kinesin 1 regulated
It is inactive when there is no ATPase activity and it will become active upon receptor binding
What is cytoplasmic dynein involved in
Retrograde transport
What has ATPase in cytoplasmic dynein
The heavy chains and the stalk which is apart of the head
What do the linker and stem do in cytoplasmic dynein
Interact with dynactin to recognize and bind cargo the
What does ATP hydrolysis do in cytoplasmic dynein
Results in a shape change that drives movement
Which end does cytoplasmic dynein travel too
The negative end
What is the microtubular binding domain in cytoplasmic dynein
The stalk
What do the linker and neck region do with atpase
The bend with it to move
What does dynactin do
It binds the dynein to the cargo and regulates the movement
What regulates dynactin and dynein
Dynamtin if there is to much it makes them exlpode apart
What does P150 do
It acts as glue that binds microtubules but it not a motor
Can motor protiens be cargo
YES
What does the acetylation of a lysine residue of a tubulin do
Stabalizes the MT and promotes kinesin 1 movement
What do both kinesin and dynein have in common
Both have a head region that binds to MT and is an ATP ase
Both have a neck linker region
Both have a long structure that leads to a tail that binds to cargo
What is the long structure that leads to a tail that will eventually bind to cargo in kinesin
Stalk
What is the long structure that leads to a tail that will eventually bind to cargo in dynein
Stem
What are cilila and flagella
Two versions of the same thing
Cilia is shorter
Flagella is longer
Flagella propel cells
Cilia sweep materials
What is an axonome
The underlying structure of cilia and flagella
What is the array of microtubules
9 plus two in the middle
What does nexin do
Hold the doublets in place
What is bending
Is it localized and only some of these doublets bend
What does the radial spoke head do
Holds things in place
What does axonemal dynein do
It is permantly bound to the A tubule and is permantly pointing to the B tubule
What is the a tubule
Has 13 microtubules
What is the B tubule
Has 10 microtubules
What is the difference between axonme and basal body
Axnome doesnt have c go through the basal body are triplet microtubulers and 9 triplets and the axnomes are doublets
What does the basal body do
It is the base that anchors cilia and flagella that anchors them to the cell and serves as the template for the axonome
What is the transtional zone
The change from basal body to axoneme
How do you know how many doublets there will be
It is the amount of number triplets
How do axonemes bend
Generated by sliding of microtubules against each other powered by axonemal dyein
What part of dynemin is attached to which part of the tubules in bending
The tail is attached to the A tubule and the head binds to B
What microtubule moves
B
What happens if nexin is there
No sliding occurs so bending does
Which ways do microtubulers when sliding
In slding the B tubule moves to the positve ed and the a tubule bound moves to the negative end same with bending
What does intraflagellar transport do
Moves things up and down they are long projections and secrete ligands
Is intraflagellar transport releated to bending
NO
What do interphase contain and what is it used for
A non motile cilium no axonemal dynein but plays an important role in cell-cell signaling
What are signals rlly important in
Embryo cells
What does non motile mean
NO NEXIN OR DYNEIN
How many non motile cilia do cells have
1
What are primary cilia stabilized by
Acetylated tubulin
Where are primary cilia not found in
Mitotic cells
What is karyokinesis
Dividing up chromosomes microtubular mitosis is 2 compartments
What is cytokinesis
Dividing cytoplasm actin
What is XMAP15 involved in
Regulating the assembly of microtubules it stimulates growth binding to the ends of them and stimulating tubulin to join on
Why does XMAP-15 activity decrease during mitosis
Help control the growth and stability and for organzing the mitotic spindle which is essential for seprating chromsones correctly and you want them to be unstable so they are dynamic
What is the kinetochore
It is what chatches the chromsones
What is the zone of interdigitation
Where the chromosomes and meet and come together
What are astral MT
They are going away from it
What are the polar MT
They are not attached to chromosomes
What is a centromere
Attachment site for microtubules
What does spindle formation require
Motors and MT dynamics
What does Kinesin 7 do in spindle formation
Assisting with growth pushing to the + end
What does Kinesien 13 and dynein do
Depolymerization or shrinkage of chromsomes
What does tension assure
Bi-orientation that chromosomes are attached to both spindle poles
What happens when there is no tension
Phosphorylation of Ndc8 at kinetochore by Aurora B result in weak microtubule interactions with the kinetochore
What happens under tension
Aurora B does not phosphorylate and Ndc remains bound to the MT
What is bound to the PM
The dynein
What does the active corical anchor do
Does allow dynein to pull it in that direction
What does Kinesin 13 do in anaphase
Shrinakge and 4 also helps
What is anaphase driven by
Disassembly which is de polymerization chromsomes move closer to spindel
What is Anaphase B
Is used by motors and it pole sepration
What are astral microtubulers shortened by
Dynein
What are kinetochore microtubulers shrink by
Kinesin 4 and 13
What do polar microtubules help localize
RhoGTP which allows for the formation of a contractile acit myosin ring
