Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, Hebrew University, Jerusalem, Israel
Computational Structural Biology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
J Gen Physiol. 2018 May 7;150(5):671-682. doi: 10.1085/jgp.201711980. Epub 2018 Apr 17.
The H-coupled vesicular monoamine transporter (VMAT) is a transporter essential for life. VMAT mediates packaging of the monoamines serotonin, dopamine, norepinephrine, and histamine from the neuronal cytoplasm into presynaptic vesicles, which is a key step in the regulated release of neurotransmitters. However, a detailed understanding of the mechanism of VMAT function has been limited by the lack of availability of high-resolution structural data. In recent years, a series of studies guided by homology models has revealed significant insights into VMAT function, identifying residues that contribute to the binding site and to specific steps in the transport cycle. Moreover, to characterize the conformational transitions that occur upon binding of the substrate and coupling ion, we have taken advantage of the unique and powerful pharmacology of VMAT as well as of mutants that affect the conformational equilibrium of the protein and shift it toward defined conformations. This has allowed us to identify an important role for the proton gradient in driving a shift from lumen-facing to cytoplasm-facing conformations.
H 耦联囊泡单胺转运体（VMAT）是一种对生命至关重要的转运体。VMAT 将单胺类神经递质血清素、多巴胺、去甲肾上腺素和组胺从神经元细胞质中包装到突触小泡中，这是神经递质释放的关键步骤。然而，由于缺乏高分辨率结构数据，对 VMAT 功能的详细了解受到了限制。近年来，一系列基于同源模型的研究揭示了对 VMAT 功能的重要见解，确定了有助于结合位点和运输循环特定步骤的残基。此外，为了描述结合底物和偶联离子时发生的构象转变，我们利用了 VMAT 的独特而强大的药理学，以及影响蛋白质构象平衡并将其推向特定构象的突变体。这使我们能够确定质子梯度在驱动从管腔面向细胞质面向构象转变中的重要作用。
