Transmembrane Protein Expression Service
Membrane proteins play crucial roles in life activities such as molecular transport, signal transduction and energy utilization. On the one hand, they can be used to transmit signals from the external environment to the cell. On the other hand, they act as receivers to collect signals about the external environment. The multifunctionality of transmembrane proteins makes them ideal targets for drug action, and multiple transmembrane target proteins with full-length intact structures are of great importance.
As a biotechnology company that expresses and purifies membrane proteins (e.g., GPCRs, ion channels, transporters, enzymes, and viral targets) not currently available in the marketplace, Beta Lifescience is dedicated to addressing the unmet needs in drug discovery for treatments and cures for human diseases involving membrane proteins.
Functions of Transmembrane Proteins
Among the many genes in the genome, 20% to 30% encode genes that encode membrane proteins. Numerous membrane proteins are involved in almost every life activity in the cell, including ligand-receptor binding, signal transduction, molecular transporter, intercellular recognition and enzyme catalysis, etc., and have a wide range of applications in biological research and drug development. Different types of transmembrane proteins possess different functions. These include G protein-coupled receptors (GPCRs), ion channels, transporter proteins, and other types of receptors. These proteins play different roles within the cell, for example in signalling, substance transport and cellular communication.
GPCRs are a class of transmembrane proteins widely found in living organisms that recognise and interact with external molecules to trigger a variety of intracellular signals, which is why they are used as targets for drug screening. Ion channels, on the other hand, regulate the concentration of ions inside and outside the cell, such as sodium, potassium, and calcium ions, which are essential for the proper functioning of the cell. Transporter proteins, on the other hand, assist in the transmembrane transport of substances and regulate the metabolism of organisms. Although these transmembrane proteins have different functions, they play unique and indispensable roles in organisms.
Figure 1. Schematic diagram of transmembrane proteins
Directions for the Application of Transmembrane Proteins
Transmembrane proteins are important in cell biology and medicine. They are key components of cell membranes and are responsible for essential physiological functions such as material transport, signaling and cell recognition. Moreover, they play a central role in signaling and intercellular communication, regulating cellular responses through the interaction of receptors and signaling molecules. Abnormal function of transmembrane proteins is associated with a variety of diseases, including cancer, cardiovascular disease and neurodegenerative diseases, and is therefore an important target for drug development and therapy. In addition，Transmembrane proteins participate in various physiological activities in plants, including signal transduction, substance transport, and energy conversion.
1. Drug Targeting and the Role of Transmembrane Proteins as Drug Receptors
In recent years, the global drug research and development has been advancing by leaps and bounds, with both old and newly discovered targets, and transmembrane proteins as the most important drug targets at present. According to statistics, more than 50% of the approved drugs on the market target membrane proteins, accounting for more than 60% of the known drug targets. For antibody drug targets, membrane proteins account for more than 90%. For example, EGFR, VEGFR, HER2, LAG3, GPCR, TIGIT, BCMA, CLDN 18.2 and so on. As in Figure 2(a) antibodies activate GPCRs, acting as ligand activators or facilitators of dimerisation; antibodies inhibit GPCRs, e.g. by competing with ligands for sites.
2. Genetic Disorders Linked to Transmembrane Protein Mutations
Transmembrane proteins (TM) are a family of proteins that span the cytoplasmic membrane of cells and allow cell-cell and cell-environment connections, communication. It is associated with a variety of diseases such as cystic fibrosis, atherosclerosis, Parkinson's disease and Alzheimer's disease. For example, the quadruple transmembrane protein TMEM216 leads to impairment of primary cilia by regulating the Hedgehog signalling pathway, which in turn induces a variety of disorders such as polycystic kidneys, neurodevelopmental abnormalities, blindness, obesity, etc. As shown in Figure 2(b). In addition, TMEM216 interacts with other transmembrane proteins, but its function and related pathogenic mechanisms are poorly understood.
3. Transmembrane Proteins in Energy Conversion and Photosynthesis
The three-dimensional structure of the photosynthetic reaction centre, as shown in Figure 2(c), was determined by X-ray diffraction analysis. It contains four subunits: L, M, H and a cytochrome. Of these, the L and M subunits form the centre of the complex, and each subunit contains five helices of α spanning the lipid bilayer. The results of the analysis of the bacterial photosynthetic reaction centre are of general importance for membrane studies. Many membrane proteins involved in photosynthesis, proton pumping and electron transfer are even larger than the photosynthetic reaction centre.
Figure 2. (a)Antibody activation of GPCR targets as ligand activation or pro-dimerisation;(b)TMEM216 deletion inhibits the Hh signalling pathway;(c)Three-dimensional structure of the photosynthetic reaction centre.
Transmembrane Protein Expression and Preparation
Multiple transmembrane proteins are difficult to prepare due to their complex structures, multiple hydrophobic transmembrane regions and extremely low expression levels in host cells. It is necessary to use suitable expression vectors, host cells, culture conditions and purification processes to optimize the expression and purification process, so as to obtain efficient, high-purity and correctly conformed transmembrane protein products. Commonly used transmembrane protein expression systems include E. coli expression system, yeast expression system, insect cell expression system and mammalian cell expression system.
Figure 3. Flow chart of transmembrane protein preparation
With the development of modern drug research, the demand for transmembrane proteins is getting higher and higher, and the traditional method of transmembrane protein preparation can no longer meet the needs of modern drug research and development.At present, four major transmembrane expression technology platforms have been built, which have successfully achieved efficient expression and purification of multiple transmembrane proteins. These platforms include virus-like particles (VLP), detergent micelle, nanodisc and Cell-Free Protein Synthesis system (CFPS).
Figure 4. Comparison of four major transmembrane protein platforms
Difficulties in the Preparation of Transmembrane Proteins
Transmembrane proteins have great potential market value and medical significance as important targets for drug research and development. However, the preparation of transmembrane proteins faces many constraining bottlenecks, including low membrane protein expression, poor stability, low solubility and problems encountered in purification.
- Low expression: Transmembrane proteins are usually expressed in low amounts compared to cytoplasmic proteins. Transmembrane proteins have to be correctly folded and embedded in cell membrane sites to perform their normal functions.
- Structural complexity: Transmembrane proteins have complex structures, including multiple transmembrane regions, cyclic structures, and glycosylation modifications, all of which increase the difficulty of preparing transmembrane proteins.
- Low solubility: Since transmembrane proteins are usually embedded in lipid bilayers, they tend to have low solubility in solution. This greatly increases the difficulty of extracting and purifying transmembrane proteins
Drug Target Classes of Current Drug Therapies
Membrane proteins are important targets for numerous drug discovery and clinical therapeutic studies. Ion channels, transporter proteins, GPCRs and kinases are the largest class of drug targets in drug discovery and development, with approximately 40% of existing approved antibody drugs exerting their pharmacological effects by targeting GPCR complexes. Membrane proteins such as receptors and ion channels are key regulators of cellular function. Membrane proteins account for two-thirds of known druggable targets, underscoring their critical importance in pharmaceuticals. The largest and most versatile class of membrane receptors is the G protein-coupled receptors (GPCRs), which are also the most important drug targets, accounting for more than 50 percent of all human drug targets, and are therapeutic targets for a wide range of diseases, including cancer, cardiovascular, metabolic, central nervous system, and inflammation. Ion channels are another important class of membrane protein drug targets, accounting for 10% of the activity of currently marketed drugs.
Figure 5. Drug target classes of current drug therapies
Beta Lifescience has been working with pharmaceutical, biotechnology, and academic customers and collaborators since its founding, providing membrane protein-related products and services that advance its customers’scientific objectives.
Advantages of Our Membrane Protein Production Service
- Beta Lifescience has rich experience in membrane protein research, and the advantages of our service include the following:
- Short experimental period: Thanks to optimized procedures, we can supply the membrane proteins required by customers in the shortest possible time.
- Diverse expression systems: We have a variety of membrane protein expression systems, and the most appropriate system can be selected according to customers' needs for membrane protein production.
- High activity: Our platform enables membrane proteins to be crystallized in their native conformation, preserving their function and activity.
- Unique service: We provide complete membrane protein production services, and can also offer membrane protein crystallization and cryo-electron microscopy services.
