Signal transduction: G proteins, receptors, secondary messengers

Question 1

Mechanisms of intercellular communication

Answer 1

Autocrine: the cell produces hormone that attaches to its own receptor

Contact: signalling cell in direct contact with the target cell

Paracrine: one cell(signalling cell) produces mediators that neighbouring cells detect

Synaptic: mediators=nuerotransmitters in synapse(neuron->axon->synapse)

Endocrine: hormone from signalling cell attaches to receptor on distant cell

Question 2

Characteristics of Receptors

Answer 2

• Bifunctional: they both recognise the ligand and produce a biological response in the target cell
• Have high affinity: reversible binding to their mediators
• Receptor ligand binding is able to be saturated
• 10^-9 M ligand concentration where ligand stimulates receptor
• If Kd is lower it means the binding affinity is higher

Question 3

agonists

Answer 3

increase biological response and increases affinity of ligand to active receptor

Question 4

antagonists

Answer 4

reduce biological response, these can be allosteric or competitive

eg)agouti related peptide(AGRP)

Question 5

Inverse agonist

Answer 5

reduces activity and increase affinity of ligand to inactive receptor

Question 6

neutral antagonist

Answer 6

doesn’t effect constitutive activity

Question 7

constitutive activity

Answer 7

Biological response is induced even in absence of ligand

Question 8

Potency

Answer 8

measured by EC50 or the ligand concentration at 50% biological response

Question 9

Efficacy

Answer 9

Max biological response

Question 10

partial agonist

Answer 10

only partial biological response