L11

Question 1

what are 2 pathological hallmarks of AD

Answer 1

plaques and tangles

Question 2

what does amyloid precursor protein usually get cleaved by

Answer 2

alpha and gamma secretase

Question 3

what does amyloid beta do

Answer 3

This is toxic and it clumps together to form plaques. These kill all the cells around them (these are also toxic in their soluble form)

Question 4

what happens to Tau in AD

Answer 4

TAU proteins usually stabilise microtubules.

These proteins become phosphorylated and then the microtubules fall apart and the TAU gets clumped together

Question 5

what are the 3 stages of Tau mediated neurodegeneration

Answer 5

1. Hyperphos of tau leading to disassembly of MTs causing axonal transport
   insufficiency
2. Tau aggregates in
   axons/dendrites which congest axonal
   transport
3. Tau pathology
   transmitted
   synaptically

Question 6

describe the chronological relationships among Alzheimer’s disease
pathology and clinical symptoms

Answer 6

both Tau phosphorylation and beta amyloid start happening in the preclinical phase

however Tau phosphorylation starts happening before BA but happens slowly

BA generation happens latter but more rapidly

Question 7

what are the similarities between AD and diabetic neuropathy

Answer 7

they both disrupt protein structure –

disrupt structure =
disrupt function causing clinical symptoms

once symptoms appear it maybe too late for recovery

Question 8

what does the nissl stain, stain

Answer 8

rER (therefore soma in neurons)

Nissl was found to be selective for
RNA and so represents large stacks
of rough endoplasmic reticulum

Question 9

what are proteins involved in, in neurons

Answer 9

axonal transport and phospholipid bilayer (the proteins in it)

Question 10

describe the Phospholipid bilayer

Answer 10

hydrophobic ends in middle zone

hydrophilic ends –intra/extracellular
compartment

!not permeable to ions!
- it is this reason that neurons have so many proteins as the need so many ion channels

Question 11

what are the 2 types of channels

Answer 11

a simple channel

a complex folded structure composed of subunits (same/different)

Question 12

all cells have proteins in the membrane. why in neurons do they produce significantly more than other cells

Answer 12

neurons have a huge membrane area

´Epithelial cell

• 20µm soma diameter
• membrane area 1,256µm2

neuron
- 20µm soma diameter
- membrane area 250,000µm2
therefore it is 200x greater membrane area

to make these proteins there is lots of RER

also have specialised vesicles

Question 13

why are membrane proteins are essential components of

neuronal structure

Answer 13

• are essential for neuronal function therefore proteins need to be in the ‘right’ place and any change may result in dysfunction

Question 14

what hold the transmembrane protein in the correct place in the membrane

Answer 14

Transmembrane protein –> scaffolding protein –> actin mesh

Question 15

what technique is used to identify and locate proteins

Answer 15

immunohistochemistry

Question 16

what does immunohistochemistry tell us

Answer 16

where the protein is, where it is held/located (cellular level)

Question 17

how does immunohistochemistry work

Answer 17

first you would take a protein of interest from a rat and inject it into a goat. The goats immune system would then produce antibodies to this foreign object (protein of interest). This is called the primary antibody

We then produce a secondary antibody which is just a generic goat antibody (because the primary is specific to the protein of interest so we don’t know what it is made up of. The secondary we do therefore we are able to produce a morker to see the secondary antibody

Question 18

what is the point of the primary antibody when we have the secondary antibody

Answer 18

We don’t just send the general goat antibody (secondary) because the protein of interest might be in a hard place to get to therefore you want a specific antibody to be produced so that it is alse to reach it.

The second reason why we do it this way is so that we can amplify the signal

Question 19

what is ankG

Answer 19

it is a scaffolding protein in the proximal axon and nodes

Question 20

what is Caspr

Answer 20

• transmembrane protein
• member of neurexin family
• cell adhesion

This is in very specific locations

Question 21

what is MAP2

Answer 21

• microtubule associated protein
• absent in most astrocytes

MAP 2 is specific for dendrites

Question 22

what is PO

Answer 22

• Myelin protein

Question 23

why is actin often yellow in immunohistochemistry

Answer 23

Dendritic spine morphology (green)

F-actin (red)

Merged red and
green are shown in yellow.

because actin is what is in the dendritic spines

Question 24

why do we want to know protein location

Answer 24

because it helps to understand their function

Question 25

why do we use immunohistochemistry

Answer 25

Using Immunohistochemistry we can identify multiple proteins in multiple locations -> precision of function and a range of functions

Question 26

what is found at a chemical synappes

Answer 26

presynaptic = specialised membrane with active zones where neurotransmitter is released cleft = matrix fibrous proteins postsynaptic = specialised membrane with receptors for neurotransmitters therefore the synapse is a complex membrane specialisation

Question 27

what does the presynaptic membrane contain

Answer 27

* Calcium channels * Docking proteins * Transporter proteins * Reuptake transporter * Specific vesicle proteins

Question 28

what does the postsynaptic membrane contain

Answer 28

Voltage gated channels Transmitter-gated ion channels

Question 29

what is an example of why we have postsynaptic densities NMDA receptor

Answer 29

NMDA receptor- transmitter gated ion channel it has a complex protein - post synaptic density PSD-95 - scaffold protein, under the plasma membrane for the clustering of receptors, ion channels etc.

Question 30

what are some examples of cleft proteins

Answer 30

Trans-synaptic proteins Mind the gap (MTG) - binding protein cell adhesion molecules

Question 31

where is mind the gap protein secreted from

Answer 31

Secreted presynaptically and crosses the gap to the post synaptic density

Question 32

what do cell adhesion molecules interact with

Answer 32

interact with molecules on | surface of adjacent cell

Question 33

why do we have local protein synthesis

Answer 33

because if everything was made in the soma and then transported down the axon (anterograde by kinesin) then it would take forever

Question 34

where does local protein synthesis happen

Answer 34

at the post syanptc membrane

Question 35

how does local protein synthesis happen

Answer 35

The repressed mRNA gets attached onto the motor protein and via kinesin it is attached to the actin network and is transported to where it needs to go the mRNA then goes to the polyribosomes which make the protein

Question 36

what is Fluorescence in situ hybridization (FISH)

Answer 36

you insert a florescent probe which is complimentary to the sequence of interest then you can see where the protein is being made showing the localization of the mRNA at presynaptic sites,

Question 37

what can identify newly synthesised proteins form mature proteins

Answer 37

PLA labeling

Question 38

how many synapses are there in dendrites per micrometer

Answer 38

4

Question 39

how many receiving synapses per neuron

Answer 39

10,000

Question 40

how many output synapses per neuron

Answer 40

100,000

Question 41

why do we have local protein synthesis

Answer 41

morphological complexity, the volume, and the capacity of the neurons Remember it takes a day to get from the soma to the axon therefore we need local protein synthesis Therefore it is about getting that processing of information within minutes not hours/days

Question 42

how many different proteins are there at a synapse

Answer 42

2500

Question 43

why does the brain use so much energy

Answer 43

because of the protein demand