Cell Signalling Pathways Flashcards
How are cell signals classified
The distance they travel
What are the 3 types of cell signals
Auto rinse, Paracrine, Endocrine
What are autocrine signals
Signals that act on the same cell that secretes them
What are paracrine signals
They bind to receptors on nearby cells
What are endocrine signals
Hormones secreted by cells which target specific farther away cells
What are the 2 types of cell signalling chemicals
Hydrophobic and hydrophilic
What are hydrophobic signalling chemicals brought to the cell by? And why can they not do it by themselves
Carrier proteins, and because they cannot stay freely in the ECM
Where do hydrophilic cell signals bind to? And why that site?
Receptors on the cells surface. Because they cannot pass through the cell membrane
What are the 3 stages of cell signalling
Reception, transduction, response
What are the main types of cell signal receptors
G-protein coupled receptor, nuclear receptor, ion channel receptor, enzyme coupled receptors
What is the structure of G-proteins coupled receptors
Seven-pass transmembrane receptor and a G-protein
What 3 subunits is the G protein made
Alpha, beta, gamma
What molecule is the alpha subunit of G-protein bound to when it is dis activated
GDP
What happens when a ligand binds to the receptor of G-coupled receptor
The alpha subunit leaves the G-protein. This causes GDP to be exchanged for GTP. The alpha subunit then exerts an influence on another protein. After doing this, it recombines with the G-protein and GTP is hydrolysed to GDP, disactivating the G-protein
What type of molecule are cell-signals
Ligands
What does adrenaline binding to the b2-adrenoreceptor cause
Bronchodilation
What happens when adrenaline binds to the a1 receptor
Vasoconstriction of blood vessels
What happens when adrenaline binds to the a1 receptor
Vasoconstriction of blood vessels
What happens when adrenaline binds to the a2 receptor
Relaxation of GI tract
What happens when adrenaline binds to the b1 receptor
Increased heart rate and cardiac muscle contraction
What happens when adrenaline binds to the b3 receptor
Thermogenesis in skeletal muscle
What drug is used to treat acute cases of bronchoconstriction
Salbutamol
Why is adrenaline not a suitable drug for acute asthma attacks
The adrenaline would binds to all adrenoreceptors, causing a wide range of side effects
What is the treatment given for chronic bronchoconstriction issues
Theophyline
What is the structure of enzyme coupled receptors
2 domains, one receptor and one enzyme domain
What enzyme is usually at the enzyme domain of an enzyme-coupled receptor
Kinase
Why do enzyme coupled receptors form dimers
Because they can’t phosphorylate their own tyrosine. So they dimerise and cross-phosphorylate each other
What does cross-phosphorylation cause in enzyme coupled receptors
An increase in affinity for their binding sites
How do ligand-gated ion channels work
Ligand binds to the receptor opening the channel, ions can then flor through
What do ligand-gated ion channels modulate
Fast synaptic excitation
Where are nuclear receptors normally found
In the nucleus of target cell, bound by steroid hormones
What 2 domains do nuclear receptors contain
Ligand binding domain and dna binding domain
What does activation of nuclear receptors cause
The transcription of key proteins
What is the nicotinic acetylcholine receptor an example of
A ligand gated ion channel
What drug is useful for helping nicotine and why
Varenicline, because it is a partial agonist so can act antagonistically when paired with nicotine
What is the insulin receptor an example of
An enzyme-linked receptor
How many pathways can an enzyme-linked receptor lead to
Multiple
How many pathways can a g-protein associated receptor bind to
1
What feature of G proteins makes them have a large tissue response
Signal amplification
