Spinelli S, Ramoni R, Grolli S, Bonicel J, Cambillau C, Tegoni M
Architecture et Fonction des Macromolécules Biologiques, UPR 9039, CNRS, IFR1, Marseille, France.
Biochemistry. 1998 Jun 2;37(22):7913-8. doi: 10.1021/bi980179e.
The X-ray structure of the porcine odorant binding protein (OBPp) was determined at 2.25 A resolution. This lipocalin is a monomer and is devoid of naturally occurring bound ligand, contrary to what was observed in the case of bovine OBP [Tegoni, M., et al. (1996) Nat. Struct. Biol. 3, 863-867; Bianchet, M. A., et al. (1996) Nat. Struct. Biol. 3, 934-939]. In this latter protein, a dimer without any disulfide bridges, domain swapping was found to occur between the beta- and alpha-domains. A single Gly (121) insertion was found in OBPp when it was compared to OBPb, which may prevent domain swapping from taking place. The presence of a disulfide bridge between the OBPp beta- and alpha-domains (cysteines 63 and 155) may lock the resulting fold in a nonswapped monomeric conformation. Comparisons with other OBPs indicate that the two cysteines involved in the OBPp disulfide bridge are conserved in the sequence, suggesting that OBPp may be considered a prototypic OBP fold, and not OBPb.
猪嗅觉受体结合蛋白（OBPp）的X射线结构在2.25埃分辨率下被确定。与牛OBP的情况不同[Tegoni, M., 等人（1996年）《自然结构生物学》3, 863 - 867；Bianchet, M. A., 等人（1996年）《自然结构生物学》3, 934 - 939]，这种脂质运载蛋白是单体，且没有天然存在的结合配体。在后者的蛋白质中，一种没有任何二硫键的二聚体，发现β结构域和α结构域之间发生了结构域交换。与OBPb相比，在OBPp中发现了一个单一的甘氨酸（121）插入，这可能会阻止结构域交换的发生。OBPp的β结构域和α结构域之间存在一个二硫键（半胱氨酸63和155），这可能会将所得的折叠锁定在一个非交换的单体构象中。与其他OBP的比较表明，参与OBPp二硫键的两个半胱氨酸在序列中是保守的，这表明OBPp可能被视为一种典型的OBP折叠，而不是OBPb。
