Second Messengers, Such as Calcium Ions (Ca²⁺), Are Chemical Mediators

Second messengers, such as calcium ions (Ca²⁺) , are chemical mediators commonly used in intracellular signaling pathways. Despite its common usage in many different cell types in the body, Ca²⁺ has specific effects in lymphocytes following antigen receptor stimulation. The specific responses of lymphocytes to increased concentrations of intracellular Ca²⁺ are determined by:

A) The expression of a specific subset of Ca²⁺-responsive enzymes in lymphocytes compared to other cell types
B) The increased expression of calmodulin in lymphocytes compared to other cell types
C) The presence of enzymes that bind calmodulin in lymphocytes but not other cell types
D) The high levels of Ca²⁺ in the endoplasmic reticulum of lymphocytes compared to other cell types
E) The ability of Ca²⁺ to amplify signaling pathways in lymphocytes but not other cell types