Immunofluorescence Staining.

This unit provides a protocol for indirect immunofluorescence, which is a method that provides information about the locations of specific molecules and the structure of the cell. Antibody molecules for a specific target molecule are exposed to the cell or tissue being investigated. The binding of these molecules is detected by incubating the sample with a secondary antibody specific for immunoglobulin molecules and conjugated to a fluorophore. This provides both a visible signal and amplification of the signal and the results are observed with a fluorescence microscope. This unit describes the widely used and powerful technique of localization of proteins in cells by immunofluorescence. The location can be determined by double labeling with an antibody directed against a protein of known location. The technique can be used as a supplement to immunolocalization by electron microscopy and subcellular fractionation. It allows not only identification of the antigen distribution in the cell but also a survey of the dynamic aspects of protein movements in the cell-on and off membranes, into and out of the nucleus, and through membrane traffic pathways.