Light-harvesting photosynthetic tetrapyrrole chromophore-protein from the phycobiliprotein complex. Heterotetramer of 2 different alpha chains and 2 identical beta chains. The subunit composition could comprise any combination of 2 out of 4 different alpha units with an invariant beta unit. Contains three covalently linked phycoerythrobilin chromophores. The light-harvesting system in Cryptophytes contains phycobiliprotein complexes. Unusually they are composed of either phycoerythrin (CPE) or phycocyanin (CPC) but never allophycocyanin (APC), with only one type of biliprotein being present in any one species. Unlike cyanobacteria or red algae these proteins are not arranged into higher-order phycobilisome complexes, and they are found in the thylakoid lumen. Belongs to the phycobiliprotein family.