Sandbox Reserved 820: Difference between revisions
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The contractions of cardiac myocytes are triggered by the increase of calcium concentration in the cytosol. This phenomenon is highly controlled at several levels. First the calcium is stocked in a cell compartment called the sarcoplasmic reticulum. Then the release of calcium in the cytosol is dependent of the myocytes membrane depolarization. Finally the release of calcium is extremely brief, as soon as the depolarization is over, the calcium is actively pumped in the sarcoplasmic reticulum. | The contractions of cardiac myocytes are triggered by the increase of calcium concentration in the cytosol. This phenomenon is highly controlled at several levels. First the calcium is stocked in a cell compartment called the sarcoplasmic reticulum. Then the release of calcium in the cytosol is dependent of the myocytes membrane depolarization. Finally the release of calcium is extremely brief, as soon as the depolarization is over, the calcium is actively pumped in the sarcoplasmic reticulum. | ||
The calsequestrin 2 plays a major role here, because it helps the release of the calcium in the cytosol while the membrane depolarization occurs and traps the calcium inside the lumen of the sarcoplasmic reticulum. <ref name="CASQ2 role">NCBI Ressource: CASQ2 calsequestrin 2 http://www.ncbi.nlm.nih.gov/gene/845</ref> | The calsequestrin 2 plays a major role here, because it helps the release of the calcium in the cytosol while the membrane depolarization occurs and traps the calcium inside the lumen of the sarcoplasmic reticulum. <ref name="CASQ2 role">NCBI Gene Ressource: CASQ2 calsequestrin 2 http://www.ncbi.nlm.nih.gov/gene/845</ref> | ||
It is also good to notice that a huge release of calcium in the cytosol would be lethal to the cell, since the calcium would precipitate with the free phosphate groups. | It is also good to notice that a huge release of calcium in the cytosol would be lethal to the cell, since the calcium would precipitate with the free phosphate groups. | ||
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Each monomer is divided in <scene name='56/568018/Monomer_structure/5'>3 thioredoxin domains (TRX)</scene>: <scene name='56/568018/Monomer_structure/7'>the N-term</scene>, <scene name='56/568018/Monomer_structure/6'>the middle</scene> and the <scene name='56/568018/Monomer_structure/8'>C-term</scene> domains. Each of these has a regular structure: a <scene name='56/568018/Beta_sheet/4'>5 strands beta sheet core</scene> surrounded by <scene name='56/568018/Alpha_helix/3'>4 alpha helices</scene>.<ref name="Martin">PMID:7788290</ref> | Each monomer is divided in <scene name='56/568018/Monomer_structure/5'>3 thioredoxin domains (TRX)</scene>: <scene name='56/568018/Monomer_structure/7'>the N-term</scene>, <scene name='56/568018/Monomer_structure/6'>the middle</scene> and the <scene name='56/568018/Monomer_structure/8'>C-term</scene> domains. Each of these has a regular structure: a <scene name='56/568018/Beta_sheet/4'>5 strands beta sheet core</scene> surrounded by <scene name='56/568018/Alpha_helix/3'>4 alpha helices</scene>.<ref name="Martin">PMID:7788290</ref> | ||
Usually these domains are involved in redox phenomena, which lead to disulfide bounds creation. Here these domains are inactive but play an important role in the polymerization of CASQ2.<ref name=" | Usually these domains are involved in redox phenomena, which lead to disulfide bounds creation. Here these domains are inactive but play an important role in the polymerization of CASQ2.<ref name="Monomere structure">NCBI Structure Ressource: CASQ2 calsequestrin 2 http://www.ncbi.nlm.nih.gov/Structure/cdd/cddsrv.cgi?ascbin=8&maxaln=10&seltype=2&uid=239372&querygi=429544235&aln=1,227,0,109</ref> | ||
=== Polymer Structure === | === Polymer Structure === | ||
