Calmodulin

Calmodulin
3D structure of Ca2+-bound calmodulin (PDB: 1OSA​)
Identifiers
Symbol	CaM
PDB	1OSA
UniProt	P62158
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The helix–loop–helix structure of the calcium-binding EF hand motif

Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. It is an intracellular target of the secondary messenger Ca²⁺, and the binding of Ca²⁺ is required for the activation of calmodulin. Once bound to Ca²⁺, calmodulin acts as part of a calcium signal transduction pathway by modifying its interactions with various target proteins such as kinases or phosphatases.