Mechanical properties of actin tubulin and

 What make the intermediate filaments?
 Structure of Intermediate Filament Polypeptides?

 Centrosome
o serves as the microtubule organizing center
 Proteins that can stabilize the growing microtubule or cause it to
rapidly disassociate
o MAP (microtubule associated protein)
o Catastrophin
 Microtubule motor proteins: they move vesicles and organelles
o Kinesins (go towards plus end)
o Dyneins (go towards minus end, “dying”)
 Microtubules and mitosis:
o Microtubules help to align chromosome during mitosis
o Microtubules along with motor proteins separate daughter
chromosomes as well as push the two centrosomes apart
 Kinesin helps to push the microtubules away from each other
 Dynein pulls the centrosome to one side of the membrane
Actin
Assembly doesn’t come from just one point it can come any where in the cell , what
actually happens is actin there are proteins that tells where the branch will start
they allways have a sertn , you can control where actin polymerize
 Structure
o Actin fibers like microtubules are unstable
o Made stable by interactions with other proteins “actin binding proteins”
o Differential interactions determine “stiffness” of the structure
o Highly organized
 Formins and actin-related proteins (ARPs) control actin assembly
 Actin motor protein : Myosin ( contracting the cell )
o Slide actin filaments over each other = shortening of actin bundle
o The myosin head “walks” towards the actin plus end of the actin
causing contraction
 Cell movement:
o