These streptavidin conjugates are prepared from phycobiliproteins, light-harvesting components of the photosynthetic apparatus found in certain types of algae and cyanobacteria. Phycobiliproteins harvest the light very efficiently; their molar extinction exceeds that of any known organic fluorescent dye by one or two orders of magnitude, and they fluoresce with extremely high quantum efficiency.

Fluorescent streptavidin conjugates can be used to detect biotinylated proteins in Western blot experiments, protein arrays, and more.