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Nat Struct Biol. 1998 Jun;5(6):476-83.

Crystal structure of calsequestrin from rabbit skeletal muscle sarcoplasmic reticulum.

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Department of Biochemistry and Biophysics, Washington State University, Pullman 99164-4660, USA.


Calsequestrin, the major Ca2+ storage protein of muscle, coordinately binds and releases 40-50 Ca2+ ions per molecule for each contraction-relaxation cycle by an uncertain mechanism. We have determined the structure of rabbit skeletal muscle calsequestrin. Three very negative thioredoxin-like domains surround a hydrophilic center. Each monomer makes two extensive dimerization contacts, both of which involve the approach of many negative groups. This structure suggests a mechanism by which calsequestrin may achieve high capacity Ca2+ binding. The suggested mechanism involves Ca2+-induced collapse of the three domains and polymerization of calsequestrin monomers arising from three factors: N-terminal arm exchange, helix-helix contacts and Ca2+ cross bridges. This proposed structure-based mechanism accounts for the observed coupling of high capacity Ca2+ binding with protein precipitation.

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[Indexed for MEDLINE]

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