Phycobiliproteins are found in cyanobacteria (also known as blue-green algae) and algae groups such as rhodophyta (red algae) and cryptophytes. Major phycobiliproteins include variations of phycocyanin (blue-pigment), variations of phycoerythrin (red pigment), and allophycocyanin (light-blue pigment); each of them possessing different spectral properties.  These water-soluble biliproteins are not essential for the functioning of cells. Some special qualities of phycobiliproteins include antioxidant properties and high fluorescence, and it is their chromophores that give these proteins their strong pigment. Phycobiliproteins are classified into two categories based on their amino-terminal sequences: "α-type" and "β-type" sequences. In biliproteins where the number of bilins on the two subunits is unequal, the subunit with more bilins has a β-type amino sequence.