Crystallization of rat cellular retinol binding protein II. Preliminary X-ray data obtained from the apoprotein expressed in Escherichia coli.
Rat cellular retinol-binding protein II (CRBP II) is a member of a family of cytoplasmic proteins which bind hydrophobic ligands. CRBP II is thought to participate in the intestinal absorption and intracellular metabolism of retinoids. We have previously described the crystallization of a homologous rat intestinal fatty acid-binding protein (I-FABP) isolated from Escherichia coli containing a suitably constructed prokaryotic expression vector (Sacchettini, J. C., Meininger, T. A., Lowe, J. B., Gordon, J. I., and Banaszak, L. J., J. Biol. Chem. 262, 5428-5430). We have now efficiently expressed rat CRBP II in E. coli. The E. coli-derived protein, which does not contain any bound retinoid, has been purified and crystals grown from solutions of polyethylene glycol 4000. Crystals of apo-CRBP II are triclinic, space group P1, a = 36.8 A, b = 64.0 A, c = 30.4 A; alpha = 92.8 degrees, beta = 113.5 degrees, gamma = 90.1 degrees. Each unit cell contains two molecules of the 134-residue apoprotein. X-ray diffraction data suggest that the unit cell parameters of crystalline apo-CRBP II resemble those of I-FABP. Comparison of the tertiary structures of E. coli-derived rat I-FABP and CRBP II should provide insights about how these proteins evolved to bind different hydrophobic ligands.
Sacchettini
J C
JC
Department of Biological Chemistry, Washington University School of Medicine, St. Louis, Missouri 63110.
Stockhausen
D
D
Li
E
E
Banaszak
L J
LJ
Gordon
J I
JI
D000818:Animals; D002352:Carrier Proteins; D003001:Cloning, Molecular; D003460:Crystallization; D004926:Escherichia coli / Q000235:genetics; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D051381:Rats; D012177:Retinol-Binding Proteins / Q000235:genetics; D054840:Retinol-Binding Proteins, Cellular; D014961:X-Ray Diffraction
D002352:Carrier Proteins; C490174:Fabp7 protein, rat; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D012177:Retinol-Binding Proteins; D054840:Retinol-Binding Proteins, Cellular