Lecture Set 14

Question 1

What is the largest class of enzyme-coupled receptors?

Answer 1

RTK –> receptor tyrosine kinases
have large extracellular and intracellular domains
single transmembrane helix
dimerize

Question 2

Describe how the RTK works

Answer 2

ligand binds to receptor, activates it and causes it to dimerize with another active receptor. This leads to autophosphorylation where the other’s tyrosine groups are phosphorylated. From here, it activates GRB2 and Sos that activates Ras that leads to Raf then Mek then MAPK activates Jun/ETS that leads to gene regulation

Question 3

What is the SH2 domain

Answer 3

domain that the molecules have in common, area where the RTK binds

Question 4

Describe the IP3 pathway of RTK

Answer 4

RTK activates PLCgamma that activates IP3

Question 5

What happens when Ras is mutated?

Answer 5

becomes an oncogene, slows down GTPase activity which keeps Ras turned on (gain of function mutation)

Question 6

What is a scaffolding complex?

Answer 6

protein that brings all the steps in a cascade close together for speed/efficiency

Question 7

What are receptor serine/threonine kinases

Answer 7

have 2 type 1 (phosphorylation) domains and 2 type 2 (kinase) domains that group together through ligand binding, and then phosphorylates R-Smad which binds Smad 4 to regulate gene expression

Question 8

Describe the two types of Adrenergic receptors

Answer 8

Alpha connected to Gq results in activation of PLC
beta connected to Gs, results in increase in cAMP, PKA which phosphorylates phosphorylase kinase that phosphorylates glycogen phosphorylase b converting it to glycogen phosphorylase a
glycogen phosphorylase b degrades glycogen

Question 9

what is the difference between type 1 and 2 diabetes?

Answer 9

type 1 = insufficiency of insulin, type 2 = insensitive to insulin

Question 10

How is glucose levels regulated?

Answer 10

balance between insulin and glucagon, insulin receptor is an RTK