title: Crystallization of canine cardiac calsequestrin.
abstract: Calsequestrin is the major Ca2+ binding protein in the lumen of the sarcoplasmic reticulum membranes. Two X-ray quality crystal forms of canine cardiac calsequestrin were obtained by the hanging drop method using KCl as a precipitant. One form is monoclinic (space group P2(1), a = 73.4 A, b = 104.4 A, c = 60.2 A, beta = 120.4 degrees) with two molecules in the asymmetric unit and a solvent content of approximately 40%. The second form is trigonal (P3(1)21 or P3(2)21, a = b = 99.3 A, c = 89.8 A) with a single molecule in the asymmetric unit and 55% solvent content. Cross rotation function calculations show that despite the different space groups the packing of the molecules in both crystals is likely to be similar suggesting the existence of a stable dimer. The monoclinic crystals diffract beyond 3 A using a laboratory rotating anode source, while under the same conditions the trigonal crystals diffract only to approximately 4.5 A. This is the first report of successful preparation of X-ray quality crystals of a high capacity Ca2+ binding protein.
authors.affiliation: Group in Protein Structure and Function, Medical Research Council of Canada, Edmonton, Alberta.
authors.forename: K
authors.initials: K
authors.lastname: Hayakawa
authors.forename: L
authors.initials: L
authors.lastname: Swenson
authors.forename: S
authors.initials: S
authors.lastname: Baksh
authors.forename: Y
authors.initials: Y
authors.lastname: Wei
authors.forename: M
authors.initials: M
authors.lastname: Michalak
authors.forename: Z S
authors.initials: ZS
authors.lastname: Derewenda
mesh_terms: D000818:Animals; D002155:Calsequestrin / Q000737:chemistry* / Q000302:isolation & purification; D003460:Crystallization; D018360:Crystallography, X-Ray / Q000379:methods; D004285:Dogs; D009206:Myocardium / Q000378:metabolism*; D011487:Protein Conformation; D012519:Sarcoplasmic Reticulum / Q000378:metabolism
chemical_list: D002155:Calsequestrin