The Alexa Fluor 633 goat anti—mouse IgG is labeled with our bright, photostable Alexa Fluor 633 dye and is prepared from affinity-purified antibodies that react with IgG heavy chains and all classes of immunoglobulin light chains from mouse. To minimize crossreactivity, it has been adsorbed against human IgG and human serum prior to conjugation. We also provide another version of the same antibody that has been cross-adsorbed against additional species (A-21052). Fluorescence of this long-wavelength Alexa Fluor dye is not visible to the human eye but is readily detected by most imaging systems.