Primary antibodies, secondary antibodies and controls for western blotting
The primary antibody usually recognizes a specific protein or epitope and is conjugated or tagged to a fluorescent dye or an enzyme to enable subsequent detection. The tagged antibodies are detected directly (direct western blotting) or using secondary antibodies (indirect western blotting). Depending on the method, secondary detection is carried out using antibodies conjugated to enzymes or fluorophores. Horseradish peroxidase (HRP) is the most common enzyme used for tagging.