Biological Signalling Molecule and Receptors Flashcards
What are the 3 systems that use chemical messenger signalling?
- Paracrine
- Nervous
- Endocrine
Describe signalling in the Paracrine, Nervous and Endocrine systems
Paracrine - Signals act locally by matrix diffusion
Nervous - Neurotransmitters travel within a defined synaptic junction
Endocrine - Hormones travel between endocrine cells via the bloodstream
What is a ligand and what is a receptor?
Ligand - Binds specifically to a receptor site
Receptor - Recognises a specific ligand and binding results in cellular process regulation (activation or inhibition)
Identify 2 roles of a receptor
- Neurotransmission
- Cell Adhesion
- Gene Expression Control
- Hormone Signalling
- Immune Response Modulation
Name two types of receptor
- Acetylcholine
- Muscarinic
What are the two types of ligand and what effect do they have?
Agonist - activates a receptor
Antagonist - binds without causing activation
Name the 2 receptors which affect cardiac pacemaker cells and the effect they have on heart rate
Acetylcholine - Reduces heart rate
Noradrenaline - Increases heart rate
What does a ligand have a high affinity than at enzyme binding sites?
Substrates and allosteric regulators
What is the difference between a receptor and an acceptor?
Receptor - Silent at rest and agonist binding stimulates a response
Acceptor - Operate in ligand absence, binding has no effect
What are the four major types of receptor?
- Integral Ion Channels
- Integral Enzyme Activity
- Transducing G-Proteins
- Intracellular
Name 2 characteristics, a receptor and an effect of an Integral Ion Channel
C - has 5 subunits, fastest type of signal transduction, closed in silent state
R - GABA, Glycine
E - opens K+, Na+, Cl- channel
What are the two domains of an Integral Enzyme Receptor and do they work alone?
- Catalytic and Binding Domain
- Work in pairs
Name 1 receptor and 1 enzyme involved in Integral Enzyme Receptors
R - Insulin, ANP Receptor, Epidermal Growth Factor
E - Tyrosine Kinase, Guanylyl Cyclase
What is the main process that involves Integral Enzyme Activity?
Protein Phosphorylation
What is the largest class of receptor?
G-Protein Receptors
How many subunits does a G-Protein Receptor have?
7 subunits
What is the process when a G-Protein Receptor is activated?
- GDP on G-protein dissociates
- GDP turns into GTP
- Phosphate released by GTP
- Phosphates binds to and activates the enzyme
Give an example of a G-Protein process
- Adrenaline activates Adenylyl Cyclase
- Acetylcholine stimulates K+ channel to open
Name 2 products of an Intracellular Receptor Pathway
- Cortisol
- Oestrogen
- Progesterone
What is the ligand in intracellular signalling?
A hormone
What is released when a ligand binds in Intracellular signalling?
Inhibitory protein
What is the final stage in Intracellular Signalling?
DNA binding site opens and transcription occurs
