Streptavidin-Cy3 may be used in conjunction with biotinylated antibodies in immunohistochemistry and immunocytochemistry. Cy3 is excited maximally at 554 nm, emits at 568-574 nm, and can be used with the traditional rhodamine filter arrangements due to the spectral overlap. Cy3 has a molar extinction coefficient of 1.3 × 105 M.
