4: II

Question 1

How many junction types are there at the cell-cell, what are their sub groups and name

Answer 1

3

tight, cell/cell anchoring (adherens + desmosome), gap (channel)

Question 2

How many junction types are there at the cell-matrix, what are their sub groups and name

Answer 2

cell-matrix anchoring junction

- actin linked, hemidesmosome

Question 3

where does the intracellular adaptor proteins sit in pathway

Answer 3

(b/w cytoskeleton filaments + transmembrane adhesion proteins)

Question 4

name the basic parts to the junction pathway

Answer 4

extraceullar ligand > transmembrane protein > intracellular adaptor > intracellular cytoskeleton filament

Question 5

What does the Cell/Cell and Cell-matrix adhesion have in common

Answer 5

Both cytoskeletal filament is actin

Question 6

what does the hemidemone and desmosome have in common

Answer 6

both cytoskeletal filament is intermediate filament

Question 7

Name the different Transmembrane protein for all 4 junctions

Answer 7

• cell/celladhesion= cadherin
• cell/matrix adhesion = intergrin
• desmosome = non class cadherin (desmoglein, desmocollin)
• hemidesmosome- 2 intern + 1 collagen xvii

Question 8

Name the different intracellular adaptor protein for all 4 junctions

Answer 8

• cell/celladhesion= catenin/vinculin
• cell/matrix adhesion = talin, vinculin (FAC)
• desmosome = plakophilin, plakoglobin, desmoplakin
• hemidesmosome- Plectin

Question 9

Describe the Cell-cell adherens junction

Answer 9

1. cells join at cadherins (transmembrane)
2. cadherin links to a/b catenin
3. catenin a binds to actin/ or vinculin

Question 10

Describe the actin linked Cell-matrix junction

Answer 10

1. a/b integrin joins to ECM proteins
2. integrin b binds to talin
3. talin binds to actin + vinculin

Question 11

how does actin link to nuclear envelope

Answer 11

links to nesprin + nespron links to nuclear lamina

Question 12

Describe the desmosome junction

Answer 12

1. 2 cells joins at non classical cadherin (desmocollin + desmoglein)
2. desmoglen/collin join to plakophilin
3. plakopilin binds to plakoglobin + desmoplakin
4. these bind to intermediate filla

Question 13

Describe the hemidesmosome junction

Answer 13

1. ECM proteins binds to two integrin + one collagen xvii
2. integrin/collagen bind to plectin
3. plectin binds to intermediate filament

Question 14

what sort of adhesion does cahejrins allow and what does that mean

Answer 14

• Cadherins mediate homophilic adhesion

• i.e. same cadherin must bind to same cahderin

Question 15

describe cadherin + Ca2+

Answer 15

joined by calcium at hind regions + if removed= floppy and will not join

Question 16

how does cadherin aid in development

Answer 16

attach to like cadherins + // are able to guide organisation of developing tissues
i.e cells expressing N cadherin move to one section + those expressing E cadherin move to another

Question 17

what 2 types of matter does cadherins sort

Answer 17

Both Qualitative and Quantitative matter 
// can seperate 2 colonies, also uses gradient to cause inner/outer expression

Question 18

what occurs when alpha catenin is extended

Answer 18

1. Alpha catenin extended
2. Exposes site for vinculin
3. Vinculin adds actin = greater pulling force

Question 19

describe cadherin in Contraction dependent tissue remodelling

Answer 19

coordinated contraction of actin across adhesion belt = aids in morphogenesis + folding of epithelial cells

Question 20

example of a intermediate filament

Answer 20

keratin

Question 21

describe mouse mutation claudin 1

Answer 21

fail to make tight junctions between the cells in the epidermal layer of the skin; as a result, the baby mice lose water rapidly by evaporation through the skin and die within a day after birth.

Question 22

describe gap juntion

Answer 22

• Connects both electrically and metabolically

Question 23

how to determine size of gap junction

Answer 23

using fluorescent molecules of various sizes

Question 24

what are gap junctions formed by

Answer 24

• Formed by 2 connexons which connect across the intercellular space

Question 25

describe activation of integrin

Answer 25

A + beta chains interlock // prevents talin attaching + so inactive