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Title: Casq2  
Author: World Heritage Encyclopedia
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Subject: Calsequestrin, Catecholaminergic polymorphic ventricular tachycardia
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calsequestrin 1 (fast-twitch, skeletal muscle)
Calsequestrin monomer showing the three repeating calsequestrin domains
Symbol CASQ1
Alt. symbols CASQ
Entrez HUGO OMIM PDB 1A8Y (RefSeq UniProt Locus q21
calsequestrin 2 (cardiac muscle)
Symbol CASQ2
Entrez HUGO OMIM RefSeq UniProt Locus p13.3-p11
crystal structure of calsequestrin from rabbit skeletal muscle sarcoplasmic reticulum at 2.4 a resolution
Symbol Calsequestrin
Pfam Pfam clan InterPro PROSITE PDOC00675

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. [1] 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 (Calsequestrin-2/CASQ2) is present in cardiac and slow skeletal muscle and the fast skeletal form (Calsequestrin-1/CASQ1) is found in fast skeletal muscle. The release of calsequestrin-bound calcium (through a calcium release channel) triggers muscle contraction. The active protein is not highly structured, more than 50% of it adopting a random coil conformation.[2] When calcium binds there is a structural change whereby the alpha-helical content of the protein increases from 3 to 11%.[2] Both forms of calsequestrin are phosphorylated by casein kinase 2, but the cardiac form is phosphorylated more rapidly and to a higher degree.[3] Calsequestrin is also secreted in the gut where it deprives bacteria of calcium ions.

See also


Further reading

External links

  • GeneReviews/NCBI/NIH/UW entry on Catecholaminergic Polymorphic Ventricular Tachycardia
  • Medical Subject Headings (MeSH)

This article incorporates text from the IPR001393

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