20_Cell Junctions

Question 1

From apical to basal, what is the order of junctions in the junctional complex?

Answer 1

Tight junctions (zonula occuldens)
Adherens junctions
Desmosomes (macula adherens)

Question 2

At which junction are the membranes of two cells closest together?

Answer 2

tight junctions

Question 3

The blood brain barrier is an example of which junction?

Answer 3

tight junctions

Question 4

What is an example of a tight junction protein that if mutated, results in dehydration?

Answer 4

claudin-1

Question 5

Which junctions contribute to cell polarity?

Answer 5

tight junctions form barriers that block protein movement

Question 6

Adherens junctions connect the external environment with the ______ cytoskeleton.

Answer 6

actin

Question 7

What is an example of an adherens junction protein?

Answer 7

cadherin

Question 8

Which adapter proteins link cadherins in adherens junctions to actin filaments?

Answer 8

catenins (ß-catenin, a-catenin, p120 catenin)

Question 9

Desmosomal cadherins anchor to _________.

Answer 9

keratin intermediate filaments

Question 10

Which adapter proteins allow anchoring of desmosomal cadherins to keratin?

Answer 10

plakoglobin, desmoplakin, plakophillin

Question 11

What are two desmosomal cadherins?

Answer 11

desmoglein, desmocollin

Question 12

How do connexin proteins form gap junctions?

Answer 12

6 connexins form a connexon (transmembrane channel with central pore)
2 connexons form a gap junction

Question 13

Gap junctions provide hydro (philic/phobic) channels.

Answer 13

hydrophilic

Question 14

Which junctions connect cells to the ECM?

Answer 14

hemidesmosomes & focal adhesions

Question 15

Which cytoskeleton do focal adhesions interact with?

Answer 15

keratin

Question 16

Which cell-substratum interactions are involved in cell motility and survival signalling?

Answer 16

focal adhesions

Question 17

In focal adhesions, what do ECM proteins do cellular integrins interact with?

Answer 17

collagen and fibronectin

Question 18

In hemidesmosomes, which anchoring protein do the cell’s integrins interact with on the ECM side?

Answer 18

laminin