Signalling through proteolysis (4)

Question 1

what is Wnt signalling ?

Answer 1

signalling through a ligand called Wnt (secreted protein)

Question 2

what does Wnt signal through ?

Answer 2

canonical pathway -
planar cell polarity (PCP) pathway
Ca2+ pathway

Question 3

Canonical Wnt signalling.. what is Wnt

Answer 3

stimulus

Question 4

Frizzled and Lrp5/6

Answer 4

receptor

Question 5

Dishevelled

Answer 5

Effector

Question 6

B-catenin

Answer 6

Transcription factor

Question 7

What happens when there’s no Wnt ?

Answer 7

B-catenin undergoes proteolysis

Question 8

B-catenin forms a complex with 1.

Answer 8

1.Axin

Question 9

B-catenin forms a complex with 2.

Answer 9

2. Adenomatous Polyposis Coli

Question 10

B-catenin forms a complex with 3.

Answer 10

3. Glycogen synthase kinase 3

Question 11

B-catenin forms a complex with 4.

Answer 11

Casein Kinase 1alpha

Question 12

B-catenin forms this complex which undergoes ?

Answer 12

phosphorylation and proteolysis

Question 13

At rest what is concentration B-catenin ?

Answer 13

very low

Question 14

At rest, what stops the transcription of the genes that Wnt will eventually cause to to be expressed ?

Answer 14

Groucho

Question 15

What prevents B-catenin proteolysis ?

Answer 15

Wnt

Question 16

How does Wnt prevent proteolysis ?

Answer 16

by preventing B-catenin proteolysis - when Wnt binds to frizzled dishevelled is recruited which steals Axin therefore B-catenin proteolysis doesn’t occur.

Question 17

What ultimately occurs when Wnt binds to frizzled ?

Answer 17

B-catenin levels increase which is a transcription factor

Question 18

Why is Wnt signalling important ?

Answer 18

Crucial for embryonic development and nerve circuits

Question 19

Hedgehog Signalling.. what are they and how many types are there ?

Answer 19

Secreted proteins

Three types: sonic, indian, desert.

Question 20

What is Hedgehog ?

Answer 20

Stimulus

Question 21

Patched ?

Answer 21

Receptor

Question 22

Smoothened

Answer 22

Effector

Question 23

Cubitus interruptus/Gli (mammalian)

Answer 23

transcription factor

Question 24

what does cubits interrupts undergo at rest ?

Answer 24

proteolysis

Question 25

what does cubits interrupts do in the resting state ?

Answer 25

represses transcription

Question 26

during hedgehog signalling what happens?

Answer 26

inhibiting Ci proteolysis stimulates transcription - Ci full length now

Question 27

what inhibits proteolysis ?

Answer 27

Smoothened activation

Question 28

At rest what inhibits smoothened ?

Answer 28

patched which is the receptor

Question 29

what de-inhibts smoothened ?

Answer 29

Hedgehog ligand when its bound to patched

Question 30

what happens when you prevent proteolysis ?

Answer 30

transcription

Question 31

what does hedgehog signalling do ?

Answer 31

regulates the polarity of segments in the embryo