Structural Dynamics of Transmembrane Signaling Complexes by Negative Stain Electron Microscopy.

Using Electron Microscopy for Studying Structures of Membrane Proteins;Biological Chemistry;Science;Biological Chemistry

Mancour, Liliya VasilevaSmith, Janet ;

University of Michigan

关键词: Using Electron Microscopy for Studying Structures of Membrane Proteins;    Biological Chemistry;    Science;    Biological Chemistry;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/100056/liliv_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

As an integral part of the cell’s communication system, membrane proteins play an essential role in relaying signals between cells and their environment. For example, binding of ligand on the extracellular portion of a cell surface receptor induces conformational changes that are transmitted through the membrane and activate numerous signaling pathways. I have utilized negative stain electron microscopy and single particle analysis to investigate and characterize the structural dynamics of transmembrane protein machineries. The hormone leptin is a key regulator of metabolism and body weight. The leptin receptor (LepR) is a single pass transmembrane receptor that is capable of instigating intracellular signaling via the JAK/STAT pathway upon leptin binding to the extracellular side of LepR. Both stimulation and inhibition of LepR have implications in disease treatment and represent important drug targets. I characterized the architecture of the leptin/LepR signaling complex and proposed a mechanism of activation upon binding of ligand. LepR displays significant flexibility in a hinge region within the leptin binding domain while the C-terminal ;;legs” remain rigid. In the context of a liganded receptor, there is no flexibility at the hinge region and the C-terminal, membrane proximal ;;legs” become positioned in a certain orientation that we propose is a key mechanism for transmitting the signaling across the membrane.This work also characterizes a signaling complex between the μ-Opioid receptor (μ-OR) and its cognate Gi subunit. The results reveal the dynamic nature of the Gα subunit of Gi, which appears to be a common feature of G-protein activation. As opioid drugs are highly addictive and their clinical efficacy restricted, understanding the activation mechanism of the µ-OR will facilitate more targeted drug development.