** Calmodulin is a small, dumbbell-shaped protein
composed of 2 globular domains. These 2 domains are connected by a flexible
linker. This linker is flexible even when it is not bound to target proteins.
This flexibility is important because it allows calmodulin to wrap around the target
protein, with the two domains on either side of it. The flexibility allows a conformational
change of
shape according to the target
proteins.
** Each domain contains TWO calcium bindind sites, so each calomodulin can bind FOUR calcliums. Each of the Ca2+ ions is surrounded in the calmodulin loop by the (-)charged sidechains of 3 aspartates, 1 glutamate, and 1 oxygen (from the protein backbone).
Calmodulin binding 4 calcium ions (
(images taken from pdb files shown) in purple).
*Picture on the left is one calmodulin binding 4 Ca+ ions in each of it's domains
*Picture on the right is a single postitive calcium ion surrounded by the negatively charged side chains of Asp and Glu.
** Each domain contains TWO calcium bindind sites, so each calomodulin can bind FOUR calcliums. Each of the Ca2+ ions is surrounded in the calmodulin loop by the (-)charged sidechains of 3 aspartates, 1 glutamate, and 1 oxygen (from the protein backbone).
Calmodulin binding 4 calcium ions (
(images taken from pdb files shown) in purple).
*Picture on the left is one calmodulin binding 4 Ca+ ions in each of it's domains
*Picture on the right is a single postitive calcium ion surrounded by the negatively charged side chains of Asp and Glu.