Membrane Proteins, Solved: How CryoEM Cracks Tough Structures

Membrane proteins are the gatekeepers and workhorses of the cell, playing crucial roles in a vast array of biological processes, including cell signaling, transport of nutrients and ions, and maintaining cellular integrity. Their dysfunction is implicated in numerous diseases, making them prime targets for drug development. However, determining the high-resolution three-dimensional structures of membrane proteins has historically been a formidable challenge due to their inherent instability outside the lipid bilayer and the difficulties in obtaining well-diffracting crystals for X-ray crystallography. Fortunately, the advent and rapid advancement of CryoEM Services have revolutionized the field of structural biology, offering a powerful toolkit to conquer these challenges and unveil the intricate architecture of membrane proteins.

Shuimu BioSciences stands at the forefront of this revolution, providing comprehensive and cutting-edge CryoEM Services that empower researchers to determine the structures of even the most challenging membrane proteins at near-atomic resolution. Founded in 2017 at Tsinghua University, Shuimu brings together world-class experts in life sciences, computational science, IT, and the pharmaceutical sectors, establishing itself as the first commercial platform in Asia offering cryo-electron microscopy (cryo-EM) structure determination. Leveraging deep research and technical heritage in structural biology, Shuimu has established efficient, advanced workflows for both experimental procedures and data analysis.

The Challenge of Membrane Protein Structures

Membrane proteins reside within the lipid bilayer of cell membranes, a hydrophobic environment essential for their stability and function. Extracting them from this environment and maintaining their native conformation for structural studies has been a major hurdle. Traditional methods like X-ray crystallography often struggle with membrane proteins due to difficulties in obtaining high-quality crystals suitable for diffraction. This is often attributed to their flexibility, heterogeneity, and the need for detergents to solubilize them, which can disrupt their native structure.

Cryo-EM: A Powerful Solution for Membrane Proteins

Cryo-electron microscopy (cryo-EM), particularly Single Particle Analysis (SPA), has emerged as a game-changer for determining the structures of membrane proteins. SPA involves rapidly freezing purified macromolecular particles, such as membrane proteins, in a thin layer of vitreous ice, thus preserving their native state. By collecting extensive two-dimensional images of these randomly oriented particles and employing sophisticated computational algorithms for processing and three-dimensional reconstruction, SPA can generate detailed high-resolution structural models.

Shuimu BioSciences offers a comprehensive One-Stop SPA Solution specifically designed to tackle the complexities of membrane protein structure determination. This integrated approach covers the entire workflow, from protein preparation and purification to data acquisition, processing, and model refinement.

Key advantages of Cryo-EM SPA that make it particularly well-suited for membrane proteins include:

• Preserves samples close to their native state: Vitrification in cryo-EM avoids the need for harsh crystallization conditions or staining artifacts, capturing membrane proteins in a near-physiological environment.

• Captures diverse conformations: Membrane proteins often exist in multiple functional states. Cryo-EM can capture and resolve these different conformations, providing insights into their dynamic mechanisms.

• Requires minimal sample volume: Compared to crystallography, cryo-EM typically requires smaller amounts of purified protein, which is often a limiting factor for membrane proteins.

• Determines heterologous protein complexes: Cryo-EM can readily analyze membrane protein complexes with other proteins, lipids, or small molecules, crucial for understanding their physiological roles.

Shuimu's Expertise in Membrane Protein Cryo-EM

Shuimu BioSciences boasts extensive experience in handling a wide range of membrane proteins, including G protein-coupled receptors (GPCRs), ion channels, and transporters. Their One-Stop SPA Solutions cater to various membrane protein targets, including those in antigen-antibody complexes, PROTACs, and VLPs.

To overcome common challenges associated with membrane protein cryo-EM, such as preferential orientation and air-water interface disruption, Shuimu leverages advanced technologies like GraFuture, GO & RGO graphene-based support grids. These innovative grids can significantly enhance the quality of cryo-EM data, particularly for difficult-to-image samples like small or low-concentration membrane proteins.

Shuimu's Cryo-EM Center is equipped with state-of-the-art 300 kV electron microscopes in both Beijing and Hangzhou, ensuring high-quality data acquisition. Their dedicated team of experienced EM scientists and engineers oversees daily operations and maintenance, ensuring optimal performance and reliable data collection. Furthermore, Shuimu has developed an AI-driven SMART software suite that streamlines cryo-EM data analysis, improving efficiency and accuracy.

Success Stories and Applications

Shuimu's commitment to high-resolution structure determination is evident in their impressive track record. They have resolved over 150 structures at a best resolution of 1.8 Å, including numerous membrane proteins. Their platform has supported the publication of numerous research results in top international journals, covering atomic-level resolution structures of ion channels and GPCRs.

Examples of membrane protein structures successfully determined using cryo-EM, supported by Shuimu's platform and partners, include:

• GPCRs: Structures of various GPCRs like GPR75, histamine H1 receptor, bradykinin receptors, and dopamine receptors have been resolved, providing crucial insights into ligand binding and activation mechanisms.

• Ion Channels: The structure of the human GluN1-GluN2A subtype NMDA receptor and human Nav1.7 have been elucidated, revealing gating mechanisms and modulation.

• Transporters: The structure and transport mechanism of human multidrug transporter MRP4 and the human calcium pump SPCA1 have been determined, offering a deeper understanding of their function.

These structural insights are invaluable for understanding the fundamental biology of membrane proteins and for guiding the development of novel therapeutics targeting these crucial molecules. Cryo-EM also plays a significant role in antibody drug development by revealing high-resolution 3D structures of antibody-antigen interactions involving membrane protein targets, aiding in the design of more effective antibody drugs.

Beyond SPA: Complementary Cryo-EM Services

In addition to SPA, Shuimu BioSciences offers other valuable CryoEM Services that contribute to the comprehensive structural analysis of membrane proteins:

• Cryo Characterization: This service utilizes ultra-low temperature technology to observe the natural state of samples like liposomes and LNPs, which are often used in the study and delivery of membrane proteins. Shuimu's self-developed AI system, NanoSMART, can automatically identify nanoparticle features, providing detailed reports on size distribution, roundness, and integrity.

• Negative Staining & 2D Negative Staining: This technique provides rapid, low-resolution structural information about membrane protein samples, allowing for initial assessments of particle homogeneity, size, and morphology, which can guide subsequent high-resolution cryo-EM studies.

Unlock the Structures of Your Membrane Protein Targets

Shuimu BioSciences is your ideal partner for unlocking the intricate structures of membrane proteins using cutting-edge CryoEM Services. With their world-class facilities, experienced team, and comprehensive suite of services, they provide the expertise and technology needed to overcome the challenges associated with these vital biomolecules.

To learn more about how Shuimu BioSciences can accelerate your research and provide high-resolution structures of your membrane protein targets, please visit our website at https://shuimubio.com/. For detailed project consultations and to discuss your specific needs, please contact our dedicated marketing team today. Let Shuimu BioSciences empower your structural biology endeavors and pave the way for groundbreaking discoveries.