Lecture 6 Flashcards
(9 cards)
What reaction does adenylyl cyclase catalyse?
ATP to cyclic AMP
What reaction does phospholipase C catalyse?
PIP2 to IP3 and DAG
What happens when adenylyl cyclase is activated?
It catalyse the conversion of ATP to cyclic AMP which then activates cyclic AMP dependent protein kinase A. PKA
How does PKA work?
It has a regulatory and catalytic domain. On cAMP binding the regulatory domains allow the catalytic domains to be released and they phosphorylase target proteins in the cell.
What happens when a G alpha q G protein is activated?
Phospholipase C is activated which converts PIP2 to IP3 and DAG. IP3 binds to the IP3 receptor in the sarcoplasmic endoplasmic reticulum and causes calcium release. This calcium then activates protein kinase C along with DAG.
Can you give an example of amplification in signalling?
Ligand to G protein to numerous adenylyl cyclase to numerous cAMP to numerous PKA’s etc.
What signalling pathway can be used to treat inotropy in the heart?
Adrenaline can bind to beta 1 adrenoreceptors in the heart. Adenylyl cyclase stimulation leads to cAMP which stimulates PKA’s which then phosphorylase voltage operated calcium channels and increased amount of calcium enter the cell which increase the ejection fraction.
Give an example of a phospholipase C signalling pathway.
Adrenaline and noradrenalne can activate alpha 1 adrenoreceptors in arteriolar to give vasoconstriction. Phospholipase C result in PIP2 separating into DAG and IP3. IP3 binds to IP3 receptors in the sarcoplasmic endoplasmic reticulum and this leads to calcium release which binds to protein kinase c which phosphorylates other proteins and results in sustained muscular contraction and vasoconstriction.
Give a example of a signalling pathway that modulates neurotransmitter release?
Morphone bindijg to micro opioid receptors and the beta and gamma subunits inhibit voltage operated calcium channels which prevents calcium influx into the presynaptic terminal and neurotransmitter release.
