>Dear dr. Grover,
Indeed, the general idea is that SERCA pumps are required for the termination of the transient calcium signal after cell stimulation together with the concerted action of PMCA pumps and/or sodium-calcium exchanger. But, let's not forget that SERCA1, SERCA2, and PMCA display high affinities for calcium and in normal condition this might be sufficient for a cell to survive the transitory increases in cytosolic calcium concentration. What about SERCA3 with its low calcium affinity? It appears it would function at 'abnormal' high calcium concentration. That's why I suggested it might be a benefit for a cell to express SERCA3 in order to overcome accidental or/and induced cytosolic calcium increases.