calcium homeostasis part 2 Flashcards
What role do Ca²⁺-ATPases play in maintaining basal Ca²⁺ levels?
actively transport calcium (Ca²⁺) out of the cytoplasm
name the 2 types of Ca-ATPase pumps
PMCA SERCA
what is the ratio of PMCA
1 H in 1 Ca out
what is the ratio of SERCA
2 H in 2 Ca out
How do Na⁺/Ca²⁺ exchangers (NCX) contribute to calcium homeostasis?
exchange three sodium ions (Na⁺) into the cell for one calcium ion (Ca²⁺) out of the cell
reduce intracell calcium levels
where is calnexin found and how many Ca binding sites does it have
ER 25
where is calsquestrin found and how many Ca binding sites does it have
SR 70
name the EF-hand motif proteins
calmodulin
S100
calcineurin
name the C2-domain containing proteins
PLC PKC PLA
what family of ATPases are Ca-ATPase apart of
P-type
what can increase activity of PMCA
calmodulin
how many splice variants of PMCA are there
4
E1= ______ calcium affinity
E2= ______ calcium affinity
high
low
phospholamban can regulate?
ATPase activity
SERCA is encoded by ___ genes
3
NCX is ___________ system
antiport
which gene encodes NCX
SLC8
how many NCX isoforms are there
3
voltage gated Ca channels are encoded by __________ gene
CACNA1
What are store-operated calcium channels (SOCs) and how are they regulated?
SOCs, such as the ORAI1 channel, are activated when calcium levels in the endoplasmic or sarcoplasmic reticulum drop. STIM1 senses this depletion and triggers the opening of SOCs in the plasma membrane to allow Ca influx. Regulation is primarily driven by intracellular calcium store depletion.
IP3 role in Ca release
PLC hydrolyses PIP2 into DAG and IP3
IP3 stimulates release of Ca from ER via ITPR
