Types of Receptors

Question 1

What are ligand-gated ion channels?

Answer 1

• Examples include ACH (nicotinic), GABA, glutamate
• Activated by small molecules (amino acids)
• Fast neurotransmission (nerve to muscle, nerve to nerve)
• Very fast movement (milliseconds)
• Signalled by the movement of ions through channel (electrical activity)

Question 2

What are G protein coupled receptors?

Answer 2

• Examples include ACH (muscarinic), dopamine, adrenaline and noradrenaline, serotonin, opioid etc)
• Activated by small molecules (some peptides)
• Role = neurotransmission, modulation of neurotransmission
• Moderately fast (secs-mins)
• Signalled by activation of enzymes and modulation of ion channels – signalling cascades

Question 3

What are Tyrosine kinase receptors?

Answer 3

Examples - Epidermal growth factor (EGF), VEGF, PDFG, TNF-a, interleukins, interferons
- Activated by peptide and proteins
- Regulate cell growth, proliferation, death
- Moderate speed
- Signalled by activation of protein signalling cascades leading to change in gene transcription

Question 4

What are Nuclear/Cytoplasmic receptors?

Answer 4

E.G- corticosteroids, sex steroids, thyroid hormone
- Activated by steroids and thyroid hormones
- Regulate gene transcriptions
- Slowest speed (days- weeks)
Signalled by gene transcription - synthesis of mRNA and protein