Effector Mechanisms Flashcards
What happens when Adenylyl cyclase is stimulated?
The enzyme causes the conversion of ATP to cyclic AMP. cAMP is highly soluble so dissolves into the cytoplasm and binds to a number of different proteins including PKA, activating its kinase activity.
What does PKA stand for?
Cyclic AMP-dependant protein kinase
What happens when Adenylyl cyclase is inhibited?
ATP is not converted into cyclic AMP
What is the structure of PKA?
It is made up of 2 regulator subunits which are attached to 2 catalytic subunits
How is PKA activated?
Increasing cAMP binds to the R(regulatory) subunits of the PKA. This then causes the catalytic subunits to be released so that they’re able to phosphorylate substrates
What happens when phospholipase C is activated?
PLC catalysed the cleavage of the membrane phospholipid PIP2 into 2 second messengers IP3 and DAG
What does the IP3 cleaved from the PIP2 molecule do?
IP3 moves through the cytoplasm to the IP3 receptor on the ER to allow calcium to move out of the ER into the cytosol
What does an increase in DAG and calcium ions result in?
The activation of PKA, which can then phosphorylate its own set of proteins
What is signal amplification?
Where relatively small changes in extracellular signals result in significant changes in cellular behaviour.
How is the intropy of the heart increased?
Both blood-borne adrenaline and sympathetically released noradrenaline can interact with a GPCR which activates Adenlylyl cyclase. The PKA activated phosphorylates a Voltage operated calcium channel allowing an influx of calcium ions.
What is inotropy in the heart?
The force in which the heart contracts
How are GPCR involved in contracting smooth muscle?
Noradrenaline, acetylcholine and other molecules utilise Gq GPCRs to activate the PKC pathway to contract smooth muscle
