Light-harvesting photosynthetic bile pigment-protein from the phycobiliprotein complex (phycobilisome, PBS). Phycocyanin is the major phycobiliprotein in the PBS rod. Heterodimer of an alpha and a beta subunit, which further assembles into trimers and the trimers into hexamers. Part of the phycobilisome rod. Two isomers exist. Contains two covalently linked bilin chromophores. Major isomer. Minor isomer. Major isomer. Minor isomer. Belongs to the phycobiliprotein family.