User:Michael Roberts/BIOL115 CaM: Difference between revisions
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== Binding to target proteins == | == Binding to target proteins == | ||
'''INACTIVE CALMODULIN:''' | '''ACTIVE & INACTIVE CALMODULIN:''' | ||
At resting levels of cytosolic Ca<sup>2+</sup> (~100 nM), calmodulin exists predominantly in the calcium-free form. This is called apo-calmodulin and <scene name='User:Michael_Roberts/BIOL115_CaM/Inactive_calmodulin/1'> | At resting levels of cytosolic Ca<sup>2+</sup> (~100 nM), calmodulin exists predominantly in the calcium-free form. This is called <scene name='User:Michael_Roberts/BIOL115_CaM/Inactive_calmodulin/1'>apo-calmodulin</scene> and its structure is more compact than the structure we saw earlier <scene name='User:Michael_Roberts/BIOL115_CaM/Structure_plus_c/3'>with bound calcium</scene>. Note the extended α-helix linking the two EF-hand-containing domains in the Ca-bound structure, which is interrupted in the <scene name='User:Michael_Roberts/BIOL115_CaM/Inactive_calmodulin/1'>Ca-free form</scene>. Here, the terminal helices are folded down concealing their hydrophobic surfaces and the central chain, which is not now α-helical along its whole length, is not exposed. | ||
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The target molecule here (shown in blue) is the calmodulin-regulated enzyme, myosin light chain kinase. Only a short sequence from this protein, the calmodulin binding domain, is shown. | The target molecule here (shown in blue) is the calmodulin-regulated enzyme, myosin light chain kinase. Only a short sequence from this protein, the calmodulin binding domain, is shown. | ||
In this view, <scene name='54/541097/Active_calmodulin/3'>polar and non-polar residues</scene> are coloured in order to highlight the hydrophobic interior of the molecule, which forms the binding site for the myosin light chain kinase calmodulin binding domain. | |||
{{Template:ColorKey_Hydrophobic}}, {{Template:ColorKey_Polar}} | |||
</StructureSection> | </StructureSection> | ||
'''External Resources.''' | '''External Resources.''' | ||
You can view a nice animation of the conformational change undergone by calmodulin upon calcium binding by following this link [http://morph2.molmovdb.org/results.rpy?jobid=8350057535]. | You can view a nice animation of the conformational change undergone by calmodulin upon calcium binding by following this link [http://morph2.molmovdb.org/results.rpy?jobid=8350057535]. | ||
