Final answer:
Proteins on gels can be visualized using PAGE and two-dimensional electrophoresis. Stains like Coomassie Brilliant Blue and silver stain are commonly used, with silver being more sensitive but complex. Immunoblotting provides specificity by using antibodies to detect targeted proteins.
Step-by-step explanation:
Visualization of Proteins on a Gel
Proteins can be visualized on a gel using various methods, with each technique presenting its own advantages and disadvantages. Among the common methods, Polyacrylamide Gel Electrophoresis (PAGE) and two-dimensional gel electrophoresis are used extensively to resolve and analyze proteins. In PAGE, proteins are separated based on their net charges or size (when treated with SDS). Two-dimensional electrophoresis combines isoelectric focusing (IEF) and PAGE to separate proteins by both their isoelectric points (pI) and molecular weights (Mr).
Staining is the most widespread method for visualizing proteins post-electrophoresis. Coomassie Brilliant Blue and silver stain are popular choices. Coomassie stain is less sensitive but easier to use and less toxic than silver stain, which is highly sensitive but more complex to perform. Additionally, proteins can be identified post-PAGE using immunoblotting (western blot) which employs antibodies to detect specific proteins.
Each method has its trade-offs regarding sensitivity, complexity, and specificity. Simple stains such as Coomassie are good for general visualization of protein bands, whereas silver staining is suited for detecting proteins present in very low quantities. Western blotting provides high specificity by using antibodies but is more time-consuming and requires knowledge of the protein to be detected.