Question

How does calmodulin activate target proteins?

Short answer

Calmodulin must bind with Ca²⁺ to be activated. Once attached to Ca²⁺, calmodulin modifies its interactions with various target proteins, such as kinases or phosphatases, to function as a calcium signal transduction cascade component.

Step-by-step solution

Activation of CaM

The binding of Ca²⁺to either domain of CaM induces a conformational change in that domain, which exposes an otherwise buried Met-rich hydrophobic patch. This patch, in turn, binds with high affinity to the CaM-binding domains of numerous Ca²⁺regulated protein kinases.

Target proteins are involved in the signal transduction pathway

Calmodulin functions as a part of a calcium signal transduction cascade by altering its interactions with a range of target proteins, such as kinases or phosphatases, after becoming coupled to Ca²⁺.