Tissue 2

Question 1

Desmosomes

1) serve what main purpose because they are subject to what?
2) Through desmosomes, what are connected
3) Homophillic interactions between what
4) How are the intermediate filaments linked with each other?
5) describe the overall structure of desmosomes

Answer 1

1) disribute tensile forces so they are present in tissues that are subject to high mechanical stress
2) The intermediate filaments of adjacent cells are connected to form a continuous network of great strength
3) Between cell adhesion molecules of the cadherin family, desmoglein and desmocollin
4) Via adaptor proteins such as plakoglobin, plakophilin and desmoplakin
5) Desmoplakin is connected to the filament. Plakoglobin is connected to both desmoplakin and plakophilin. Both Plakos are connected to the nonclassical cadherin proteins

Question 2

Cadherins can be used for what 2 things

Answer 2

Adhesion and signalling

Question 3

Intermediate filaments

1) have what formation in the cytoplasm
2) confers what type of strength
3) They are often what

Answer 3

1) criss cross cell
2) confer tensile strnegth
3) often cell specific, desmin in heart, keratin in skin

Question 4

What are two diseases involving desmosome junctions

Answer 4

Autoimmune diease
- antibodies to desmosomal proteins disrupt desmosome which leads to skin and mucosal blistering
Congenital genetic disease
- epidermolysis bullosa simplex due to mutations in keratins which alos leads to skin andmucosal blisterin

Question 5

Focal adhesions are what

Answer 5

Actin linked cell matrix junction

Question 6

Focal adhesions

1) involve what proteins (there are two types)
2) list the proteins under the two types from answer 1
3) describe the structure of the focal adhesions
4) involved in what?

Answer 6

1) Transmembrane adhesion proteins which are integrins and adaptor proteins
2) Integrins - alpha and beta sbunits of integrin
Adaptor - Vinculin and Talin
3) The integrins bind to the ECM. the integrins then pass through the membrane. The beta subunitthen binds to Talin which binds to Vinculin which in turn binds to Actin filament. Kindlin binds to the beta subunit in the cytosol
4) Involved in cell movement (cultured cells) and attachment (mytotendinuous junction)

Question 7

How do focal adhesions play a role in cell motility

Answer 7

Interaction of integrins with their substrates play an important role in cell motility via generation of cell traction forces (CTF) in combination with actin assembly and disassembly.

Question 8

Hemidesmosomes

1) do what?
2) involve what proteins
3) involved in high tensile strength adhesion to what?
4) describe the structure

Answer 8

1) Link to intermediate filaments in ECM
2) Integrins and adaptor
Integrins being alpha6beta4
Adaptor being plectin and dystonin
3) adhesion to matrix eg skin
4) Kertain filaments in epithelial cell which binds to plectin that is bound to the alpgabeta ting. The alphabeta ting is bound to laminin which then binds to the collagen in the ECM