Cytoskeleton - Part II Motor PROs (25) Flashcards
how is the movement of vesicles & molecules in the cell controlled?
where MTs are placed - growth & direction is directed by the cell
Regulation of the motors:
Activation
Placement on their paths
Movement along path
MT motor PROs?
kinesin & dynein
microfilament motor PROs?
myosin
kinesin
MT motor PRO, move towards + end of MT
Smallest of motor PROs
Pair of globular ends – generate force (walk)
Stalk & fan shaped tail binds cargo
dynein
MT motor PRO, move towards – end of MT
Ubiquitous eukaryotic motor PRO
2 identical heavy chains which generate force
Variety of intermediate & light chains with diff cargo recognition domains
Cargo is attached by dynactin
myosin
microfilament motor PRO, moves along the actin network
how is movement of kinesin & dynein facilitated?
Kinesin & dynein attach to diff adapter PROs which then attach to diff PROs in membranes (vesicles, PM etc.) to generate movement, capture cargo before movement
what 2 motor PROs are involved in ATP dependent movement?
kinesin & dynein
how is ATP movement done?
ATP binding
ATP hydrolyzing
ADP release
causes a conformational change in the motor domain & alters the orientation of the neck linker
what are the heads in motor PROs responsible for?
attachment & movement
dendrites
neuron receives signal
axons
neuron sends signals
Axon MT orientation
minus end points towards cell body & plus end outwards
what is the movement of motor PROs in neurons?
kinesin moves towards the synapse
dynein moves away from the periphery
Kinesin uses ___ ATP/step
1
Kinesin moves along:
a single protofilament
kinesin move only on ____ & ____ are left in b/w steps
betas
alphas
where does kinesin attach to the vesicle?
integral PRO
how many kinesins are found in human cells
40
how do kinesins bind to larger cargo?
aid of cargo or scaffolding PROs (Rab PROs)
how do kinesin exist in the absence of cargo?
fold over & don’t bind MTs
motor PRO ATP dependent movement (Kinesin & dynein)
Once cargo is bound, only one head with bound ADP binds to the MT
ADP is replaced with ATP on the bound head, causing the neck to pivot
Second head binds
Second head has ADP replaced with ATP & the neck bends
ATP is hydrolyzed to allow the trailing head to release from the MT
what is the effect of ATP hydrolysis in motor PROs?
enables the trailing head to release from the MT
what is the effect of swapping ADP with ATP in motor PROs?
neck will bend enabling the head to move