CaMbinding

CaMbinding refers to the interaction between calmodulin (CaM), a small, highly conserved calcium-binding messenger protein, and a wide variety of target proteins. Binding is typically regulated by intracellular Ca2+ levels and often modulates the activity, localization, or interaction networks of the target. Calmodulin contains four EF-hand motifs arranged in two lobes; binding of Ca2+ induces a conformational change that exposes hydrophobic surfaces, enabling CaM to engage target peptides or proteins.

Targets typically possess dedicated CaM-binding domains or motifs; these interactions can be Ca2+-dependent or, for some proteins, occur with apo-CaM. The affinity and outcome depend on the target and cellular context.

Functional roles: CaMbinding regulates enzymes such as CaMKII, calcineurin, and nitric oxide synthase; it modulates ion channels such as voltage-gated calcium channels where CaM mediates Ca2+-dependent inactivation; it also affects motor proteins, transcription factors, and cytoskeletal components.

Genetics and evolution: In vertebrates, calmodulin is encoded by three genes (CALM1, CALM2, CALM3) producing nearly identical proteins; CaM is highly conserved across eukaryotes. Structural and biophysical studies (NMR, X-ray) reveal how CaM wraps around helices of its targets.

Research and methods: Binding is studied using co-immunoprecipitation, peptide arrays, calorimetry, surface plasmon resonance, and structural approaches; understanding CaMbinding is essential for deciphering calcium signaling networks.