Membrane Receptors (clinical science)

Question 1

4 types of membrane receptors

Answer 1

Ligand gated ion channels
Tyrosine kinase receptors
Guanylate cyclase receptors
G protein-coupled receptors

Question 2

Ligand-gated ion channel receptors type of response

Answer 2

fast response

Question 3

Examples of ligand gated ion channels

Answer 3

e.g. nicotinic acetylcholine
GABA-A & GABA-C
glutamate receptors

Question 4

Tyrosine kinase receptors 2 types

Answer 4

receptor tyrosine kinase
non-receptor tyrosine kinase

Question 5

Receptor tyrosine kinase examples

Answer 5

insulin, insulin-like growth factor (IGF), epidermal growth factor (EGF)

Question 6

non-receptor tyrosine kinase examples

Answer 6

PIGG(L)ET:
Prolactin, Immunomodulators (cytokines IL-2, Il-6, IFN), GH, G-CSF, Erythropoietin and Thromobopoietin

Question 7

Guanylate cyclase receptors what do they contian

Answer 7

contain intrinsic enzyme activity

Question 8

Guanylate cyclase receptors example

Answer 8

atrial natriuretic factor, brain natriuretic peptide

Question 9

G protein-coupled receptors - what do they mediate

Answer 9

generally mediate slow transmission and affect metabolic processes

Question 10

G protein coupled receptors - what Hare they activated by?

Answer 10

activated by a wide variety of extracellular signals e.g. Peptide hormones, biogenic amines (e.g. adrenaline), lipophilic hormones, light

Question 11

GPCR: how many subunits?

Answer 11

consist of 3 main subunits: alpha, beta and gamma
G proteins are named according to the alpha subunit (Gs, Gi, Gq)

Question 12

Gs mechanism

Answer 12

Stimulates adenylate cyclase → increases cAMP → activates protein kinase A

Question 13

Gs examples

Answer 13

• Beta-1 receptors (epinephrine, norepinephrine, dobutamine)
• Beta-2 receptors (epinephrine, salbuterol)
• H2 receptors (histamine)
• D1 receptors (dopamine)
• V2 receptors (vasopressin)
• Receptors for ACTH, LH, FSH, glucagon, PTH, calcitonin, prostaglandins

Question 14

gi mechanism

Answer 14

Inhibits adenylate cyclase → decreases cAMP → inhibits protein kinase A

Question 15

gi examples

Answer 15

• M2 receptors (acetylcholine)
• Alpha-2 receptors (epinephrine, norephinephrine)
• D2 receptors (dopamine)
• GABA-B receptor

Question 16

gq mechanism

Answer 16

Activates phospholipase C → splits PIP2 to IP3 & DAG → activates protein kinase C

Question 17

gq examples

Answer 17

• Alpha-1 receptors (epinephrine, norepinephrine)
• H1 receptors (histamine)
• V1 receptors (vasopressin)
• M1, M3 receptors (acetylcholine)