Antibody-based methods of detecting of molecules interacting with a target molecule, such as a nuclear or cytoplasmic protein, in a fixed and, optionally, permeabilized cell or tissue sample. In one example, the target molecule is bound by a primary antibody, and a secondary, peroxidase-conjugated antibody, then binds to the primary antibody. The peroxidase may also be conjugated the primary antibody. Biotin tyramide is added to the sample, and the peroxidase generates short-lived intermediates resulting in biotinylation of molecules adjacent to the peroxidase. Biotinylated molecules can be isolated from the sample by affinity interaction with avidin- or streptavidin, resulting in a fraction containing biotinylated molecules that are located in the sample in proximity to the target molecule. The fraction can be analyzed by mass-spectroscopy, Western blotting, sequencing and other techniques.