User:Michael Roberts/BIOL115 CaM
From Proteopedia
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'''SECONDARY STRUCTURE''': This is shown more clearly by a <scene name='User:Michael_Roberts/BIOL115_CaM/Structure_plus_c/2'>ribbon diagram</scene>. The computer calculates where regions of secondary structure occur and draws them as ribbons. | '''SECONDARY STRUCTURE''': This is shown more clearly by a <scene name='User:Michael_Roberts/BIOL115_CaM/Structure_plus_c/2'>ribbon diagram</scene>. The computer calculates where regions of secondary structure occur and draws them as ribbons. | ||
The a-helical region is now clearly defined, and there are also regions of b-structure. | The a-helical region is now clearly defined, and there are also regions of b-structure. | ||
| + | {{Template:ColorKey_Helix}}, | ||
| + | {{Template:ColorKey_Strand}}, | ||
| + | {{Template:ColorKey_Turn}}. | ||
The short anti-parallel b-sheet between the adjacent EF hand loops are observed in calmodulins from various species. | The short anti-parallel b-sheet between the adjacent EF hand loops are observed in calmodulins from various species. | ||
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The structure shown has four <scene name='User:Michael_Roberts/BIOL115_CaM/Structure_plus_c/3'>Ca2+ ions</scene> bound. In this condition, the protein adopts the extended structure shown. The EF hand-forming helices are bent away from the long linking helix, revealing hydrophobic residues and exposing the linking chain. | The structure shown has four <scene name='User:Michael_Roberts/BIOL115_CaM/Structure_plus_c/3'>Ca2+ ions</scene> bound. In this condition, the protein adopts the extended structure shown. The EF hand-forming helices are bent away from the long linking helix, revealing hydrophobic residues and exposing the linking chain. | ||
| + | '''CO-ORDINATING RESIDUES''': To illustrate how Ca2+ is bound, this display shows the <scene name='User:Michael_Roberts/BIOL115_CaM/Co-ordination/1'>residues </scene>that take part in binding one of the Ca2+ ions. | ||
| - | + | <scene name='User:Michael_Roberts/BIOL115_CaM/Co-ordination/2'>'''ZOOM'''</scene> to see this more clearly. | |
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End of section | End of section | ||
</StructureSection> | </StructureSection> | ||
Revision as of 10:56, 12 April 2013
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 below, 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.
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