2D gel electrophoresis is a widely used technique in molecular biology and biochemistry to separate and analyze complex mixtures of proteins. It combines two dimensions of separation, isoelectric focusing (IEF), and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), to achieve high-resolution separation of proteins based on their isoelectric point (pI) and molecular weight. Here is a step-by-step overview of the 2D gel electrophoresis process: 1. Sample Preparation: The first step involves extracting proteins from the biological sample of interest. The sample can be a cell lysate, tissue extract, or any other protein-containing mixture. The proteins are typically solubilized and denatured using a lysis buffer containing detergents and denaturing agents. 2. Isoelectric Focusing (IEF): The next step is to perform the first dimension separation, which separates proteins based on their pI. In IEF, proteins are loaded onto an immobilized pH gradient (IPG) gel strip or a strip of carrier ampholytes with a pH gradient. An electric field is applied across the strip, causing the proteins to migrate toward their respective pI, where they become electrically neutral and stop moving. The separation occurs in a tube gel or a flat gel format. 3. Equilibration: After the completion of IEF, the IPG strip is equilibrated to prepare it for the second dimension separation. This involves treating the strip with reducing and alkylating agents to ensure proper SDS-PAGE separation and to prevent protein aggregation. 4. SDS-PAGE: In the second dimension, the equilibrated IPG strip is placed on top of an SDS-PAGE gel, which is typically a polyacrylamide gel with a concentration gradient. The proteins are separated based on their molecular weight as an electric field is applied across the gel. SDS, a detergent, denatures the proteins and imparts a negative charge to them, allowing for separation based on size. The proteins migrate through the gel, with smaller proteins moving faster and larger proteins moving more slowly. 5. Visualization and Analysis: After the electrophoresis run, the proteins are typically stained using specific dyes, such as Coomassie Brilliant Blue or silver stain, to visualize the protein bands. The gel can be scanned or photographed for documentation and further analysis. Advanced techniques like mass spectrometry can be used to identify individual proteins within the gel spots/bands. Overall, 2D gel electrophoresis allows researchers to obtain a two-dimensional map of the protein composition within a sample, facilitating the detection of differences in protein expression, post-translational modifications, and protein-protein interactions. It has been a valuable tool in various fields, including proteomics, biomedical research, and biomarker discovery.