Understanding the intricate three-dimensional structures of biological macromolecules is fundamental to life science research and drug development. Among the most challenging targets are membrane proteins and G protein-coupled receptors (GPCRs). These proteins play crucial roles in cellular communication, transport, and signaling, making them prime targets for therapeutic intervention. However, their nature – being embedded in lipid membranes – makes traditional structural biology techniques like X-ray crystallography difficult. This is where cryo-electron microscopy (Cryo-EM) emerges as a powerful solution.

Cryo-EM allows researchers to determine the high-resolution 3D structures of biological samples, including challenging membrane proteins and GPCRs, while keeping them in a near-native state. One particularly effective Cryo-EM method is Single Particle Analysis (SPA). SPA involves collecting a large number of 2D images of purified biological macromolecule particles and using sophisticated computer algorithms to process and reconstruct these images into a high-resolution 3D structural model.

The Power of Cryo-EM for Membrane Proteins and GPCRs

Cryo-EM SPA offers significant advantages for studying membrane protein structure and GPCR protein structure:

• It helps maintain samples in a state close to their native environment.
• It can capture multiple conformational states of dynamic proteins.
• It requires only a small amount of sample compared to some other methods.
• It is effective in determining the structure of heterogeneous protein complexes.

These benefits are particularly valuable for membrane proteins and GPCRs, which are often dynamic and difficult to purify in large quantities.

ShuimuBio, founded in 2017 at Tsinghua University, stands as a leading commercial platform specializing in Cryo-EM structure determination. Their core team brings together expertise from life and computational sciences, IT, and the pharmaceutical industry. As Asia's first commercial platform to offer Cryo-EM structure analysis services, ShuimuBio has developed advanced and reliable experimental procedures and data analysis workflows.

ShuimuBio's Expertise in Membrane Protein and GPCR Structural Biology

ShuimuBio provides a comprehensive suite of services tailored to the complexities of membrane protein structure and GPCR protein structure determination. Their "one-stop" SPA solution is specifically designed to handle challenging samples including membrane proteins such as GPCRs, ion channels, and transporters.

Their expertise is built upon several key pillars:

• Advanced Cryo-EM Facilities: ShuimuBio operates a large-scale commercial Cryo-EM platform, featuring 8 high-end 300kV Cryo-electron microscopes equipped with advanced detectors and accessories, located in Beijing (2 microscopes) and Hangzhou (6 microscopes). These facilities are designed for high-quality structure determination and are maintained daily to ensure optimal performance.
• Top Scientist Team: The team is composed of PhD-level scientists from leading institutions, specializing in structural biology, protein science, and computational biology. They possess deep experience in various sample types, including membrane proteins.
• Extensive Experience: ShuimuBio has accumulated significant experience with over 400 Cryo-EM projects and has resolved the structures of over 150 proteins. This includes successful structure determination of challenging targets like ion channels and GPCRs. They have successfully completed over 300 single particle projects.
• Cutting-edge Resolution: ShuimuBio is dedicated to achieving excellent resolution, having reached a best resolution of 1.8 Å and a groundbreaking 1.4 Å. They have also successfully determined the structure of proteins as small as 51kDa.
• AI-Driven Platform: ShuimuBio has independently developed the SMART software series, which utilizes AI technology to enhance the efficiency of Cryo-EM data analysis. This technology reduces machine runtime and required data volume.

Comprehensive Services for Membrane Protein and GPCR Research

ShuimuBio's services cover the entire workflow for structural studies:

1. Protein Preparation and Analysis: Recognizing that high-quality protein is essential for successful Cryo-EM, ShuimuBio offers comprehensive protein services. This includes various expression systems (E. coli, mammalian cells, insect cells, and cell-free systems). They have deep experience in the membrane protein field, including designing production and purification methods for GPCRs, ion channels, and transporter sequences. Their protein services include molecular cloning, expression, purification, and protein characterization (like SDS-PAGE, Western blot, mass spectrometry, SPR, BLI, ELISA).
2. Cryo-EM Services:
3. • "One-stop" SPA Solution: As mentioned, this service is ideal for resolving the high-resolution 3D structures of complex biological macromolecules, including membrane proteins like GPCRs, ion channels, and transporters.
   • Machine Time Service: Offering 24-hour access to their 300kV Cryo-EM microscopes in Beijing and Hangzhou, accelerating data collection for structural analysis.
   • GraFuture™ Technology: ShuimuBio has developed graphene support films to overcome challenges in sample preparation, such as preferred orientation and air-water interface damage, which are particularly problematic for smaller or low-concentration proteins, including many membrane proteins.
   • Negative Staining & Negative Staining 2D: Provides initial low-resolution imaging to quickly assess sample quality, particle size, uniformity, oligomeric state, and morphology before proceeding to Cryo-EM.
   • Cryo-characterization: Utilizes ultra-low temperature technology for high-resolution observation and analysis of nanoparticles like liposomes, LNPs, and AAVs. This is useful for characterizing delivery vehicles that interact with membrane proteins. Their NanoSMART AI system automates nanoparticle identification and analysis.
   • MicroED Solution: While primarily for small molecules, peptides, and protein microcrystals, MicroED can complement Cryo-EM by providing high-resolution data from crystalline samples.

Applications in Drug Discovery

The ability to resolve cryo em membrane protein and GPCR protein structure is invaluable for drug discovery efforts.

• Antibody Drug Discovery: Cryo-EM helps resolve the structures of antibody-antigen complexes, providing insight into recognition mechanisms and binding sites. For membrane proteins and GPCRs targeted by antibodies, this structural information is crucial for optimizing antibody design and understanding mechanisms of action.
• Small Molecule Drug Discovery: Understanding the GPCR protein structure or other membrane protein structures at high resolution is key to identifying drug binding sites (targets). Cryo-EM enables researchers to study the interaction mechanisms between small molecules and their targets, aiding in the design of highly selective and potent drugs. It also supports fragment-based drug discovery (FBDD) by revealing interaction details between small molecule fragments and protein targets.

ShuimuBio's "shelf protein list" notably includes various GPCRs, ion channels, and transporters, providing readily available, high-quality protein samples for drug screening and structural studies. Examples from their list include GPR75, GPR88, GPR35, OX-2, CCR7, and various transporters and channels.

Conclusion

Cryo-EM has revolutionized structural biology, offering unprecedented capabilities to study challenging targets like membrane proteins and GPCRs. Resolving cryo em membrane protein and GPCR protein structure provides critical insights into biological function and underpins modern drug discovery and development.

With its world-leading Cryo-EM platform, expert team, and comprehensive services from protein preparation to high-resolution structure determination, ShuimuBio is well-equipped to support researchers and companies tackling these challenging targets. Their "one-stop" solution accelerates the process from gene sequence to high-precision 3D structure.

To learn more about ShuimuBio's expert Cryo-EM services for membrane protein structure and GPCR protein structure determination, please visit https://shuimubio.com/.