Sandbox 213: Difference between revisions

In the absence of bound Ca²⁺, the helices of calmodulin pack so that their hydrophobic side chains are not exposed. In this form it is unable to interact with its targets.The C-terminal lobe of each CaM adopts a semi-open conformation that grips the first part of the IQ motif (IQxxxR), whereas the N-terminal lobe adopts a closed conformation that interacts more weakly with the second part of the motif (GxxxR). <ref name="Houdusse A, Gaucher JF, Krementsova E, Mui S, Trybus KM, Cohen C. Crystal structure of apo-calmodulin bound to the first two IQ motifs of myosin V reveals essential recognition features. Proc Natl Acad Sci U S A. 2006 Dec 19;103(51):19326-31. Epub 2006 Dec 6. PMID:[[17151196]]"/>.

[[Image:Calmodulin bound to calcium.png|right|100px]]

Apocalmodulin (ApoCaM) binds to other proteins and has other specific effects. It is essential role for life. The ApoCaM-binding proteins are a diverse group of at least 15 proteins including enzymes, actin-binding proteins, as well as cytoskeletal and other membrane proteins, including receptors and ion channels.

<ref name="Najl V Valeyev1, Declan G Bates1, Pat Heslop-Harrison1,2, Ian Postlethwaite1 and Nikolay V Kotov. Elucidating the mechanisms of cooperative calcium-calmodulin interactions: a structural systems biology approach.BMC Systems Biology 2008, 2:48 doi:[[10.1186/1752-0509-2-48]]"/>.

When the Ca²⁺ concentration falls, calcium dissociates and calmodulin is quickly released, inactivating the target. However, at least one important target protein is an exception to this rule. This is CaM-kinase II which can retain its active state after it has been activated by calmodulin.

=CaMII kinase=