Ca Signaling Flashcards
Ca is a messenger
Second
Why do Ca levels need to be carefully controlled
It’s toxic!
An overdose of Ca is what causes brain damage in strokes, muscular damage in heart attacks, etc
What is the calcium concentration outside of the cell compared to inside
~20,000x higher outside
What is the result of having such a steep [Ca] gradient
It REALLY wants to get into the cell to restore equilibrium
What are the crucial mechanisms for Ca signaling
1 - regulated Ca flow into cytoplasm (from outside cell or organelles)
2 - maintain and restore steep Ca gradient
3 - sensing Ca levels
How do we regulate Ca flow into the cytoplasm from outside the cell
Ca ion channels (voltage-dependent)
GPCR and enzyme-linked receptors
How do we regulate Ca flow into the cytoplasm from inside the cell (organelles)
Ligand-gated Ca channel
How do we restore Ca levels between inside/outside the cell
Ca pump
Na/Ca exchanger
How do we restore Ca levels between cytoplasm and organelles
Ca pump
Does restoring Ca levels take energy
Yes - ATP, because we’re going against the gradient
What is the major storage site for Ca in the cell
The ER
Where in the cell is Ca stored
ER
Mitochondria
Ca binding molecules in the cytoplasm
What are the Ca binding molecules in the cytoplasm called
calsequestrin
How many(ish) Ca ions can calsequestrin bind
70-80
Recap: who maintains a LOW concentration of free Ca
Ca pumps
Ca transporters/exchangers
Ca buffer proteins
Intracellular stores (ER, mitochondria)
