During signal transduction, fluctuations in the concentration of cytosolic calcium are controlled by A) calmodulin and phospholipase C. B) gated Ca²⁺ channels and Ca²⁺-ATPase. C) parathyroid hormone and calcitonin. D) protein kinase and phosphoprotein phosphatase.

Question

Quizplus · Accepted Answer

Fluctuations in the concentration of cytosolic calcium are controlled by gated Ca2+ channels, which allow for influx, and Ca2+ ATPases, which aid in extrusion. These mechanisms regulate the balance of calcium in the cytosol, and are essential for proper cellular function.

Answer A is partially correct, as calmodulin can bind to calcium and subsequently modify downstream effectors. However, phospholipase C is not directly involved in regulating cytosolic calcium levels.

Answer C is incorrect, as parathyroid hormone and calcitonin are hormones that regulate calcium metabolism on a larger scale, rather than within the cytosol.

Answer D is also incorrect, as protein kinase and phosphoprotein phosphatase are involved in other signaling pathways, but do not directly regulate cytosolic calcium levels.

During Signal Transduction, Fluctuations in the Concentration of Cytosolic Calcium