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+  molecules

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 binds Ca²⁺ to maintain low cytosolic Ca²⁺ concentration

Two or more Ca²⁺ ions bind to induce a conformational change and activate calmodulin