Question

How many H^+ ions are transported by the vacuole H+-ATPase pump and the vacuole H+-phosphatase pump per hydrolysis of ATP and pyrophosphate respectively?

(a) 1, 1

(b) 1, 2

(c) 2, 1

(d) 2, 2

This question was addressed to me in an interview.

This is a very interesting question from Movement of Substances Across Cell Membranes in chapter Cellular Membranes of Cell Biology

Answer 1

The correct option is (c) 2, 1

The explanation is: The vacuole H+-ATPase pump and the vacuole H^+-phosphatase pump are membrane proteins on the vacuole membrane that helps in the active transport of H^+ ions inside the vacuole. With the hydrolysis of one ATP molecule, two H^+ ions can pass through the H^+-ATPase pump. However, with the hydrolysis of one pyrophosphate molecule, one H^+ ion can pass through the H+-pyrophospatase pump.