title: Identification of a calsequestrin-like protein from sea urchin eggs.
abstract: Following studies on calcium transport by isolated smooth endoplasmic reticulum from unfertilized sea urchin eggs (Oberdorf, J. A., Head, J. F., and Kaminer, B. (1986) J. Cell Biol. 102, 2205-2210) we have purified and partially characterized a calsequestrin-like protein from this organelle isolated from eggs from Strongylocentrotus droebachiensis and Arbacia punctulata. Muscle calsequestrin from sarcoplasmic reticulum is well characterized as a calcium storage protein. The egg protein resembles calsequestrin in its behavior in purification steps, electrophoretic mobility, blue staining with Stains-all on polyacrylamide gels, and its calcium binding and amino acid composition. Purification was attained with DEAE-cellulose and hydroxyapatite chromatography. The egg protein Mr of 58,000 in the Laemmli gel system is reduced to 54,000 under Weber-Osborn (neutral) conditions, thus showing a pH dependence in its mobility, although less than occurs with muscle calsequestrins. 25% of its amino acids are acidic and 10% basic. It binds 309 nmol of Ca2+/mg of protein, within the range reported for cardiac calsequestrin. Antigenically, the sea urchin egg protein is related to cardiac calsequestrin capable of binding anti-cardiac calsequestrin antibody.
authors.affiliation: Department of Physiology, Boston University School of Medicine, Massachusetts 02118.
authors.forename: J A
authors.initials: JA
authors.lastname: Oberdorf
authors.forename: D
authors.initials: D
authors.lastname: Lebeche
authors.forename: J F
authors.initials: JF
authors.lastname: Head
authors.forename: B
authors.initials: B
authors.lastname: Kaminer
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002155:Calsequestrin / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D002845:Chromatography; D002848:Chromatography, DEAE-Cellulose; D017886:Durapatite; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006882:Hydroxyapatites; D008861:Microsomes / Q000378:metabolism; D009124:Muscle Proteins / Q000302:isolation & purification*; D010063:Ovum / Q000378:metabolism*; D012617:Sea Urchins / Q000378:metabolism
chemical_list: D000596:Amino Acids; D002155:Calsequestrin; D006882:Hydroxyapatites; D009124:Muscle Proteins; D017886:Durapatite; D002118:Calcium