Light-harvesting photosynthetic bile pigment-protein from the phycobiliprotein complex (phycobilisome, PBS). Phycocyanin is the major phycobiliprotein in the PBS rod. The alpha and beta subunits exhibit high affinity for one another and form heterodimers. These heterodimers form heterohexamers of 3 alpha and 3 beta subunits which, in turn, aggregate into a heterododecamer consisting of 2 heterohexamers. Part of the phycobilisome rod. Contains one covalently linked phycocyanobilin chromophore. Belongs to the phycobiliprotein family.