What is a primary function of calmodulin when it binds with Ca²⁺?

Calmodulin is a calcium-binding messenger protein that plays a crucial role in cellular signaling. When calmodulin binds to calcium ions (Ca²⁺), it undergoes a conformational change that allows it to interact with various target proteins, including enzymes and other proteins. This interaction can lead to the activation or inhibition of these proteins, thus influencing numerous physiological processes within the cell.

The ability of calmodulin to activate or inhibit enzymes and proteins is central to its role in calcium signaling pathways. For instance, calmodulin can activate calcium-dependent kinases, which in turn can phosphorylate target proteins and elicit a range of cellular responses, such as muscle contraction, neurotransmitter release, and various metabolic pathways.

In contrast, calmodulin does not directly activate ion channels or transport calcium ions out of the cell, although it can modulate certain ion channels in response to calcium levels. It also does not function to inhibit protein synthesis as its primary role; rather, it acts more as a mediator of signaling cascades influenced by Ca²⁺ availability. Thus, the prominent function of calmodulin upon binding with Ca²⁺ is to regulate the activity of various enzymes and proteins, leading to important physiological effects.