The Alexa Fluor 633 rabbit anti—goat IgG is labeled with our bright far-red—fluorescent 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 goat. To minimize crossreactivity, it has been adsorbed against human and rat serum proteins prior to labeling. Fluorescence of this long-wavelength Alexa Fluor dye is not visible to the human eye but is readily detected by most imaging systems.