Question

You have generated antibodies that recognize the extracellular domain of the Ca2+-pump. Adding these antibodies to animal cells blocks the active transport of Ca2+ from the cytosol into the extracellular environment. What do you expect to observe with respect to intracellular Ca2+?

(a) Ca2+-pumps in vesicle membranes keep cytosolic calcium levels low.
(b) Ca2+-pumps in the endoplasmic reticulum membrane keep cytosolic calcium levels low.
(c) Ca2+-pumps in the Golgi apparatus keep cytosolic calcium levels low.
(d) Ca2+ concentrations in the cytosol increase at a steady rate.

Answer 1

Adding antibodies that recognize the extracellular domain of the Ca2+-pump to animal cells blocks the active transport of Ca2+ from the cytosol into the extracellular environment, resulting in an increase in intracellular Ca2+ concentration.

Step-by-step explanation:

When the antibodies that recognize the extracellular domain of the Ca2+-pump are added to animal cells, they block the active transport of Ca2+ from the cytosol into the extracellular environment.

As a result, the intracellular Ca2+ concentration is expected to increase. This is because the Ca2+-pumps in the plasma membrane, which continuously remove Ca2+ from the cytosol, are blocked by the antibodies. Without these pumps, Ca2+ cannot be actively transported out of the cytosol, leading to an accumulation of Ca2+ inside the cell.