User:Michael Roberts/BIOL115 CaM

File:1cll.png

Sequence and structure of EF hands

The EF hand motif is present in a many proteins and it commonly bestows the ability to bind Ca2+ ions. It was first identified in parvalbumin, a muscle protein. Here we will have a look at the Ca2+-binding protein calmodulin, which possesses four EF hands. Calmodulin and its isoform, troponinC, are important intracellular Ca2+-binding proteins. The structure on the right, obtained by X-ray crystallography, represents the Ca2+-binding protein calmodulin. It has a dumbell-shaped structure with two identical lobes connected by a central alpha-helix. Each lobe comprises three a helices joined by loops. A helix-loop-helix motif forms the basis of each EF hand.

Click on the 'green links' in the text in the scrollable section below to examine this molecule in more detail.

Let's start with a sinmple of the protein. This shows all the bonds between the atoms that make up the protein. The wireframe view shows us all the atoms, but this can be too much detail if we're mainly interested ion the overall structure of the protein. This next veiw takes us right doewn to a minimal representation that simply traces the of the protein. The backbone includes the peptide linkages between each amino acid, along with the a-carbon atoms to which R-groups are attached. Anything in this section will appear adjacent to the 3D structure and will be scrollable.

spinqualitylabelsall models Structure of Human calmodulin (PDB entry 1cll) Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Let us color the two main forms of regular in this protein. Alpha helix appears in red, beta sheet in yellow.

Alpha Helices,  Beta Strands , Turns.