4: II Flashcards
How many junction types are there at the cell-cell, what are their sub groups and name
3
tight, cell/cell anchoring (adherens + desmosome), gap (channel)
How many junction types are there at the cell-matrix, what are their sub groups and name
cell-matrix anchoring junction
- actin linked, hemidesmosome
where does the intracellular adaptor proteins sit in pathway
(b/w cytoskeleton filaments + transmembrane adhesion proteins)
name the basic parts to the junction pathway
extraceullar ligand > transmembrane protein > intracellular adaptor > intracellular cytoskeleton filament
What does the Cell/Cell and Cell-matrix adhesion have in common
Both cytoskeletal filament is actin
what does the hemidemone and desmosome have in common
both cytoskeletal filament is intermediate filament
Name the different Transmembrane protein for all 4 junctions
- cell/celladhesion= cadherin
- cell/matrix adhesion = intergrin
- desmosome = non class cadherin (desmoglein, desmocollin)
- hemidesmosome- 2 intern + 1 collagen xvii
Name the different intracellular adaptor protein for all 4 junctions
- cell/celladhesion= catenin/vinculin
- cell/matrix adhesion = talin, vinculin (FAC)
- desmosome = plakophilin, plakoglobin, desmoplakin
- hemidesmosome- Plectin
Describe the Cell-cell adherens junction
- cells join at cadherins (transmembrane)
- cadherin links to a/b catenin
- catenin a binds to actin/ or vinculin
Describe the actin linked Cell-matrix junction
- a/b integrin joins to ECM proteins
- integrin b binds to talin
- talin binds to actin + vinculin
how does actin link to nuclear envelope
links to nesprin + nespron links to nuclear lamina
Describe the desmosome junction
- 2 cells joins at non classical cadherin (desmocollin + desmoglein)
- desmoglen/collin join to plakophilin
- plakopilin binds to plakoglobin + desmoplakin
- these bind to intermediate filla
Describe the hemidesmosome junction
- ECM proteins binds to two integrin + one collagen xvii
- integrin/collagen bind to plectin
- plectin binds to intermediate filament
what sort of adhesion does cahejrins allow and what does that mean
- Cadherins mediate homophilic adhesion
• i.e. same cadherin must bind to same cahderin
describe cadherin + Ca2+
joined by calcium at hind regions + if removed= floppy and will not join
how does cadherin aid in development
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
what 2 types of matter does cadherins sort
Both Qualitative and Quantitative matter // can seperate 2 colonies, also uses gradient to cause inner/outer expression
what occurs when alpha catenin is extended
- Alpha catenin extended
- Exposes site for vinculin
- Vinculin adds actin = greater pulling force
describe cadherin in Contraction dependent tissue remodelling
coordinated contraction of actin across adhesion belt = aids in morphogenesis + folding of epithelial cells
example of a intermediate filament
keratin
describe mouse mutation claudin 1
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.
describe gap juntion
- Connects both electrically and metabolically
how to determine size of gap junction
using fluorescent molecules of various sizes
what are gap junctions formed by
• Formed by 2 connexons which connect across the intercellular space
describe activation of integrin
A + beta chains interlock // prevents talin attaching + so inactive
