There are several strategies to visualize the antibody. For transmitted light microscopy, color development substrates for enzymes are often used. The antibody can be directly
labeled with the enzyme. However, such a covalent link between an antibody and an enzyme might result in a loss of both enzyme and antibody activity. For these reasons
several multistep staining procedures have been developed, where intermediate link antibodies are used. In this protocol use the Vectastain ABC-kit. - [Read Immunocytochemistry in Free-Floating Sections Protocol]
This protocol describes the covalent coupling of antibodies to biotin. Biotin groups bind with extremely high affinity to streptavidin and avidin, both of which are available commercially coupled with enzymes, fluorescent dyes, or iodine. A biotinylated primary antibody, therefore, can be detected with any of a wide variety of different labels. The biotinylation reaction is simple and mild, and rarely inactivates the antibody. - [Read Labeling Antibodies with Biotin Protocol]
The multiprotein-DNA complex of interest is formed using the site-specifically derivatized DNA fragment. The complex is then UV-irradiated, initiating covalent cross-linking with proteins in direct physical proximity to the cross-linking agent. Extensive nuclease digestion is performed to eliminate uncross-linked DNA and convert cross-linked DNA to a cross-linked, radiolabeled nucleotide "tag." - [Read Site-Specific Protein-DNA Photo-Cross-Linking: Analysis of Structural Organization of Protein-DNA]