Control Of Calcium Flashcards
How do calcium buffers help?
They make sure that calcium diffuses more slowly through the cell
What are trigger proteins?
Proteins that bind calcium and consequently have their function altered
Give some examples of trigger proteins
Synaptotagmin
Calmodulin
Troponin
What is the approx conc of calcium in the SR?
1mM
How come we can store so much calcium in the SR?
There are calcium binding proteins in the SR to increase the calcium capacity of the store
Eg. Calsequestrin
What affinity and capacity does SERCA have?
High affinity
Low capacity
What type of G protein is activated to increase intracellular calcium?
G alpha q
How does G alpha q act to increase intracellular calcium?
Activates phospholipase C which cleaves PIP2 to form DAG and IP3
IP3 binds to IP3 receptors on the SR and induces a conformational change so that calcium can leave the SR
What is calcium induced calcium release?
Calcium can trigger more calcium release by binding to ryanodine receptors on the SR
These will also release Ca2+ into the cell
How does Ca2+ initiate contraction?
Calcium binds to troponin C
This causes tropomyosin to undergo a conformational change and expose the myosin binding sites on the actin
This means actin and myosin can interact to contract the muscle
What affinity and capacity does the calcium uniporter in the mitochondria have?
Low affinity
High capacity
How does PMCA work?
Increase in intracellular calcium binds to calmodulin
This complex bind to PMCA and activates it
Expels calcium from the cell
