Calcium signalling Flashcards
What does CICR mean?
Calcium induced calcium release
What are the effects of CICR?
Calcium oscillations, propagated via calcium diffusion in a variety of cell types through cytoplasm or adjacent cells
How is calcium reuptaken?
by SERCA (ATPase) into ER, and by uniporter or Na/Ca exchanger NCX into the mitochondria.
What are some examples of calcium buffers?
parvalbumin
Calbindin-D28k
calretinin
What are the properties of the SERCA pump?
2 Ca per ATP consumed
3 genes
high density in ER membrane
activated by high [ca]cyt / inhibited by high [ca]ER
inhibited by phospholamban (relieved by phosphorylation)
How is calcium extruded?
by PMCA, or NCX
Plasma Membrane Calcium ATPase transports 1 Ca per ATP, with a low capacity.
NCX antiporter membrane protein (9 TM regions) is powered by Na electrochem gradient and transports 1 Ca for 3 Na ions. this has a high capacity but low calcium affinity.
What are three essential functions of active zones?
Recruitment of Ca2+ channels to enable tight coupling of APs to release by localizing calcium influx next to
the calcium sensor synaptotagmin;
Docking of vesicles at the release site;
Munc13-dependent priming of the fusion machinery
How is PMCA regulated?
phosphorylation by PKC, PKA
What are the properties of calmodulin?
Small Ca2+ sensor, 148 amino acids, 16.7kDa;
Cooperatively binds 4 Ca2+ (4 EF hands);
Pleiotropic effects;
Either it “wraps around” target domains of proteins upon Ca2+ binding OR it is part of the quaternary structure of proteins.
