Crystallization and preliminary X-ray analysis of recombinant bovine cellular retinoic acid-binding protein

Crystals of bovine cellular retinoic acid-binding protein (CRABPI) have been grown from protein expressed in E. coli. Two different crystal forms were obtained. Crystals containing protein with the ligand all-trans retinoic acid belong to space group P4₁ or P4₃, a = b = 41.36, c = 202.71 Å and diffract to 2.5 Å. Crystals of CRABP with the synthetic retinoid analogue Am80 diffract to 1.9 Å with space group P2₁ and cell dimensions a = 37.03, b = 105.93, c = 40.31 Å, β = 110.28°. Considerations in the crystallization of proteins with light-sensitive ligands are discussed.