Calmodulin

Calcium binding protein involved in intracellular calcium signalling.

Structure

Highly conserved sequence of 152 amino acids

There are four EFh domains which are responsible to bind 4 Ca²⁺  ions 

The arrangement of the Ca²⁺ binding sites are brought about by the N- and C- terminal lobes .

Calmodulin are dumbbell shaped protein where long and flexible alpha helix connects two globular domains. Each domain is assembled from two EF-hand regions attached to antiparalel beta-sheet. Ca²⁺ binds to glutamate and aspartate residues placed in the loop of EF-hand.

Function

Calmodulin functions as a multi-purpose intracellular receptor, governing many Ca²⁺  regulated processes.  

Two or more Ca²⁺ ions bind to induce a conformational change and activate calmodulin . This results in amplifying the affinity of Ca²⁺ molecule which later affects other signalling components such as Ca²⁺/calmodulin-dependent protein kinases (CaMKs), myosin light chain kinase (MLCK), phosphorylase kinase, neuromodulin and so on .