Faham Salem, Watanabe Akira, Besserer Gabriel Mercado, Cascio Duilio, Specht Alexandre, Hirayama Bruce A, Wright Ernest M, Abramson Jeff
Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095-1751, USA.
Science. 2008 Aug 8;321(5890):810-4. doi: 10.1126/science.1160406. Epub 2008 Jul 3.
Membrane transporters that use energy stored in sodium gradients to drive nutrients into cells constitute a major class of proteins. We report the crystal structure of a member of the solute sodium symporters (SSS), the Vibrio parahaemolyticus sodium/galactose symporter (vSGLT). The approximately 3.0 angstrom structure contains 14 transmembrane (TM) helices in an inward-facing conformation with a core structure of inverted repeats of 5 TM helices (TM2 to TM6 and TM7 to TM11). Galactose is bound in the center of the core, occluded from the outside solutions by hydrophobic residues. Surprisingly, the architecture of the core is similar to that of the leucine transporter (LeuT) from a different gene family. Modeling the outward-facing conformation based on the LeuT structure, in conjunction with biophysical data, provides insight into structural rearrangements for active transport.
利用储存在钠梯度中的能量将营养物质转运到细胞内的膜转运蛋白构成了一大类蛋白质。我们报道了溶质钠同向转运体（SSS）家族成员——副溶血性弧菌钠/半乳糖同向转运体（vSGLT）的晶体结构。该结构约为3.0埃，包含14个跨膜（TM）螺旋，呈向内开放的构象，其核心结构是由5个TM螺旋（TM2至TM6和TM7至TM11）组成的反向重复序列。半乳糖结合在核心结构的中心，被疏水残基与外部溶液隔开。令人惊讶的是，该核心结构与来自不同基因家族的亮氨酸转运体（LeuT）相似。基于LeuT结构对向外开放构象进行建模，并结合生物物理数据，为主动转运的结构重排提供了深入见解。
