Definitions for calsequestrin
This page provides all possible meanings and translations of the word calsequestrin
Calsequestrin is a calcium-binding protein of the sarcoplasmic reticulum. The protein helps hold calcium in the cisterna of the sarcoplasmic reticulum after a muscle contraction, even though the concentration of calcium in the sarcoplasmic reticulum is much higher than in the cytosol. It also helps the sarcoplasmic reticulum store an extraordinarily high amount of calcium ions. Each molecule of calsequestrin can bind 18 to 50 Ca2+ ions. Sequence analysis has suggested that calcium is not bound in distinct pockets via EF-hand motifs, but rather via presentation of a charged protein surface. Two forms of calsequestrin have been identified. The cardiac form is present in cardiac and slow skeletal muscle and the fast skeletal form is found in fast skeletal muscle. The release of calsequestrin-bound calcium triggers muscle contraction. The active protein is not highly structured, more than 50% of it adopting a random coil conformation. When calcium binds there is a structural change whereby the alpha-helical content of the protein increases from 3 to 11%. Both forms of calsequestrin are phosphorylated by casein kinase 2, but the cardiac form is phosphorylated more rapidly and to a higher degree. Calsequestrin is also secreted in the gut where it deprives bacteria of calcium ions.
U.S. National Library of Medicine
Acidic protein found in SARCOPLASMIC RETICULUM that binds calcium to the extent of 700-900 nmoles/mg. It plays the role of sequestering calcium transported to the interior of the intracellular vesicle.
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"calsequestrin." Definitions.net. STANDS4 LLC, 2014. Web. 23 Jul 2014. <http://www.definitions.net/definition/calsequestrin>.