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Actin filaments
-made up of actin
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actin filaments
actin monomer
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Microtubuli
- -Hollow cylinder, not used as pipe, but track for ex. motor protein to "walk" on
- -made up of tubuli heterodimers alpha tubuli + beta tubulin
- -end+ beta tubulin exposed
- -end - alpha tubulin exposed
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Actin filaments
- -made up of actin monomers
- -two strands (two strings of pearls), twisted around each other
- -more flexible than microtubuli
- -can be crosslinked by other proteins
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Intermediate filaments
- rope-like structure
- eight tetramers twisted into a ropelike filament
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Intermediate filaments
- -provide mechanical strength, for ex in axons in neurons
- -individual monomer is a long polypeptide
- -pair up in dimers
- -two dimers in a tetramer
- -tetramers are lined up in a "rope"
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Neurofilaments
- -a type of intermediate filament
- -high conc in axons
- -controls diameter of axon
- .diameter varies between different types of axons
- .diameter determine speed of electrical signal
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ALS
amyotrpic lateral sclerosis, aka
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Lon Geling's disease
- -accummulation +abnormal assembly of -neurofilaments in motor neurons
- -motor neurons die
- -cause -effect unknown
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MAPs
-Microtubuli associated proeins
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Hippocaupus
- neuron from hippocauspus (memory)
- tau-green, in axon
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Map2
orange, in cellbody+dendrites
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Alzheimers disease
- -aggregates of tau
- -called neurofibrillary tangles
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Tau and Map
- Tau in axons
- Map2 in cell body +dendrites
- -determine how tightly packed microtubuli are
- -stabalize microtubuli aganist disassembly
- -tau is shorter-microtubuli more tightly packed
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Anterograde transport
-cellbody to axon terminal
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kinesin
motor protein, anterograde transport
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retrograde transport
- -axon terminal to cell body
- -motor protein :dynein
- -no protein synthesis at axon terminal
- -organelles (mitochordia) synaptic vesicles must be transported there.
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Kinesin
- -made of two heavy chain (heads) + coiled tail-attached to cargo
- -speed 1 meter in 2-3 days
- -energy demands 1 ATP/step
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List 7 steps of kinesin
- -leading head contain adp in active site
- -head binds to microtubli-ADP is exhanged for ATP
- -necklinker changes conformation
- -lagging head is thrown forward +binds to microtubuli
- -first head (now trailing) hydrolyses ATP to ADP + pi
- .released to microtubuli
- -leading head exchange ADP for ATP
- -necklinker changes conformation lagging head thros forward then repeat
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