Sandbox 213: Difference between revisions
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[[Calmodulin]] (CaM) for Calcium-Modulated protein is an important protein that intervenes in a wide range of activities. | [[Calmodulin]] (CaM) for Calcium-Modulated protein is an important protein that intervenes in a wide range of activities. | ||
CaM is expressed in many cell types and can have different subcellular locations, including the cytoplasm, within organelles, or associated with the plasma or organelle membranes. | CaM is expressed in many cell types and can have different subcellular locations, including the cytoplasm, within organelles, or associated with the plasma or organelle membranes. | ||
Indeed,it is a small (16.7 kDa = 148 aa) and highly conserved protein that is necessary in all eukaryotic cells because it represents an essential calcium sensor with troponin C its isoform. | Indeed, it is a small (16.7 kDa = 148 aa) and highly conserved protein that is necessary in all eukaryotic cells because it represents an essential calcium sensor with troponin C its isoform. | ||
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*'''Three-dimensional structure of apocalmodulin''' | *'''Three-dimensional structure of apocalmodulin''' | ||
<Structure load='1CLL' size='300' frame='true' align='RIGHT' caption='Structure of apocalmodulin' scene='Insert optional scene name here' /> | <Structure load='1CLL' size='300' frame='true' align='RIGHT' caption='Structure of apocalmodulin' scene='Insert optional scene name here' /> | ||
[[Image:Apocalmodulin.jpg|right|200px]] | |||
In the absence of bound Ca<sup>2+</sup>, 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]]"/>. | In the absence of bound Ca<sup>2+</sup>, 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.jpg|right|200px]] | |||
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. | 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. | ||