Rod linker protein, associated with phycocyanin. Linker polypeptides determine the state of aggregation and the location of the disk-shaped phycobiliprotein units within the phycobilisome and modulate their spectroscopic properties in order to mediate a directed and optimal energy transfer. Part of 2 PBS rod complexes, the conventional CpcG-PBS rod and a photosystem I-specific CpcL-PBS rod, both of which include ferredoxin--NADP reductase (petH). CpcG-PBS has on average 3 stacked phycocyanin hexamers (PC, CpcA and CpcB). Linker CpcG connects the PC stack to the thylakoid, the hexamers are linked by 1 copy of CpcC1, 1 copy of CpcC2 and the stack is terminated by a single copy of CpcD. The CpcL-PBS has on average 5 stacked phycocyanin hexamers (PC, CpcA and CpcB). Linker CpcL connects the PC stack to the thylakoid, the hexamers are linked by 1 copy of CpcC1, 3 copies of CpcC2 and the stack is terminated by a single copy of CpcD. This protein occurs in the rod, it is associated with phycocyanin. Belongs to the phycobilisome linker protein family.