Shemanko lecture 8 Flashcards
IP3/Ca 2+ and PKC pathways
How does PLC cut phosphorylated inositol?
Uses it’s PH domain to interact with the polar head group and then couples with G protein subunit to cut it into it’s inositol group and lipid group.
As acetylcholine increases what happens to the tension of the smooth muscle?
it increases
As epinephrine increases what happens to the tension of the smooth muscle?
It decreases
Why does epinephrine cause the smooth muscle to decrease?
because in peril don’t want to be digesting things
Describe the IP3/Ca2+ and PKC pathway
- Phosphoinisotol in membrane gets phosphorylated by kinase
- Phosphoinisotol in membrane gets phosphorylated by kinase again
- acetylcholine binds to G protein coupled receptor
- The G protein binds to the receptor, gets activated by GDP to GTP
- The g protein activates the effector PLCB
- PLCB splits phosphorylated insistisol into IP3 and DAG
- DAG recruits PKC (protein kinase), stays n the plasma mebrane and helps the cell grow and differentiate
- IP3 fuses into cytoplasms and binds to IP3 receptor located on smooth ER
- This opens IP3 receptor and causes calcium ions to diffuse into cytoplasm
- Calcium triggers muscle cell contraction and some calcium fuses back to proteins to go back to the smooth ER to avoid overstimulation
What causes a calcium wave in a starfish egg?
PLC is brought into egg by sperm, cuts the present phosphoinositols, creates IP3 which causes calcium wave
How do we visualize calcium in a starfish egg?
Use fura2 which binds to calcium and shows colour changes at high (red) and low levels of calcium
How can calcium also behave as an activator of effectors and as a second messenger?
It can bind to calcium binding proteins (calmodulin) as concentration of ca rises which contains four binding sites for calcium, changing its confirmation and increasing it’s affinity for receptors.
Can also activate binding proteins such as kinases, phosphodiesterases, ion channels, or calcium transport mechanisms
