Signal Transduction Introduction Flashcards
What do signals need to be functional
Need to bind to a receptor
What do signals that can’t pass the membrane do
They transmit their signal by changing the receptors confirmation
Then Get amplified
What is signal transduction
When info from extra cellular molecules gets translated to a internal cellular signal
What are the two types of communications
Electrical
Chemical
What is electrical communication
It involves a gap junction
What is chemical communicatuon
Protiens such as hormones, neurotransmitters, growth factors
Act as a stimulus to a receptor on the plasma membrane to go from outside the cell to the inside
What is the order to transduction in chemical communication
Stimuli
Receptors
Signalling pathway:
Transducers
Amplifiers
Messengers
Sensor and effectors
Cellular responses
What is receptor based signalling
When the target cell to get the signal has a receptor that binds specific signals
The receptors are transmembrane and could also be cytosolic
What does it mean I receptors are cytosilic
The signal (ligand) has to cross the membrane on its own
What are the 4 mechanism of cell stimulus
Juxtacrine
Autocrine
paracrine
Endocrine
What is juxtacrine
Both the receiving and donating cells are membrane bound (on their recpective cells) and also very close together
What is autocrine/paracrine
The signalling and the target cell are the same cell or a neighbouring cell
Autocrine signals happen to stimulate their own receptor signal transduction
What is endocrine signalling
What are they type of signals in this type of transduction
A singal is carried throughout the body first though the blood then sent to target cells throughout the body
Ex. Estrogen, testosterone, prolactin
What are the 6 classes of receptors
G protien coupled receptor (GPCR)
Cell surface receptors
Receptor tyrosine kinases (RTK)
Steroid hormone receptors
Cytokine receptors
Ion channel receptors
What are RTK
have phosphorylated things
What are steroid hormone receptor
Receptors that are inside the cell
This is where the signal needs to travel across the plasma membrane (ex. Estrogen/testosterone)
Whit is Cytokine receptor
Immune signalling molecules bind
Dimer receptor
What are the 5 types of extracellular messengers (signals)
Amino acids and their derivatives (ex epinephrine)
Gases, NO and CO
Steroids derived from cholesterol (hydrophobic, can cross the membrane, ex. Testosterone and estrogen)
Eicosanoids that are derived from arachadonic acid
Protien ligands (most of the messengers)
What are the basic elements of cell signalling systems
Receptors on or in the target cell that recive the extracellular message
Ligands the bind to the receptor
A second messanger system the help in giving a response to the ligands or Cytoplasmic protien recruitments
What is a second messenger system
An enzyme called the effector makes the second messanger
The second messanger amplifies the signal
How does a second messenger system work
When there is no singal the second messenger is not abundant in the cell
When signal is in receptors, effectors make more and more second messengers which amplify the signal
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What are signalling pathways in signal transduction via a phosphorylation cascade
A series of protiens where each protien in the pathway changes the conformation of the next protien
The change in conformation (to be active) happens after its phosphorylated by a kinase
Can be dephisphotlsted by phosphatase
Then the target protein down the pathway eventually also gets the message and alters the activity of the cell
Why does signal transduction happen
When there is no second messenger
What is reversible phosphorylation
What things can get phosphorylated
When protien kinases transfer a phosphoryl group from atp to a substrate protein
But the protien phosphatase removes it
Ser, thr, tyr, his, arg
Start of ones I didn’t do
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How is signal transduction controlled
expression of a ligand specific receptor (only takes in specific signals)
Timing of docking protien activation
presence/absense of docking sites
Inhibitory protien that prevent certain signals
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What is the prolactin JAK STAT pathway
Is used a phosphorylation cascade
Prolactin binds to the cytokine prolactin receptor
When prolactin binds, the two receptor chains close in and dimerize, do a conformational change
After the conformational change, a tyrosine kinase next to the receptor jak2 gets activated
A phosphorylation cascade of STAT molecular happen where the STAT molecules dimerize at sh2 domains
The dimer stat molecules act as “signal transducer and transcription” factors when active
What turns off prolactin JAT STAT pathway
Phosphatase
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What is a second messenger
A non protien molecule that amplifies the signal inside the cell
