Question

Two important Calcium ATPases found within cells are the Sarcoplasmic reticulum Ca2+ ATPase (SERCA) and the Plasma membrane Ca2+ ATPase (PMCA). Both use ATP to help maintain resting calcium concentrations within cells as well as play important roles in calcium signaling.

How similar are these two calcium pumps? More specifically, how do their maximum pumping capacities compare to each other? I would assume that just because they are both calcium ATPases it does not mean they are similar in all properties. For example, the Wikipedia page linked above even mentions how

The endoplasmic reticulum calcium pump...[is] inhibited by the tumor-promoting agent thapsigargin, which does not affect the plasma membrane calcium pumps.

Have any studies been done that compares the pumping capacities of these calcium ATPases? Or maybe is there a way to determine it based on their structure, roles, etc.?

Answer 1

The Sarcoplasmic reticulum Ca2+ ATPase (SERCA) and the Plasma membrane Ca2+ ATPase (PMCA) are both calcium pumps that use ATP to maintain resting calcium concentrations within cells. SERCA has a higher maximum pumping capacity compared to PMCA. Studies have been done to compare their pumping capacities and differences in their structures and roles in cells also contribute to their different capacities.

Step-by-step explanation:

The Sarcoplasmic reticulum Ca2+ ATPase (SERCA) and the Plasma membrane Ca2+ ATPase (PMCA) are both calcium pumps that use ATP to maintain resting calcium concentrations within cells and play important roles in calcium signaling. While they are both calcium ATPases, they have different properties and functions. One difference between them is their maximum pumping capacities. SERCA has a higher maximum pumping capacity compared to PMCA. Several studies have been done to compare the pumping capacities of SERCA and PMCA. For example, a study published in the Journal of Biological Chemistry found that SERCA has higher turnover rates and faster calcium transport compared to PMCA. The differences in pumping capacities can also be inferred from their structures and roles in cells. SERCA is mainly found in the sarcoplasmic reticulum, where it pumps calcium into the reticulum. PMCA, on the other hand, is located in the plasma membrane and removes calcium from the cytoplasm. These different locations and functions contribute to their different pumping capacities.