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. Plays a role in energy transfer from the phycobilisome to photosystem I (PSI). Although able to transfer energy to both photosystems, this is predominantly a PSI antenna (PubMed:16049785, PubMed:17468217, PubMed:19152018). Part of a specialized phycobilisome (PBS), a structure that is usually composed of two distinct substructures: a core complex and a number of rods radiating from the core. This protein is part of a core-less PBS rod (called CpcL-PBS) with 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. Ferredoxin--NADP reductase (petH) is also part of the complex. CpcL-PBS has no central core proteins (allophycocyanin ApcA, ApcB) nor phycobiliprotein ApcE. Unlike the major phycobilisome supercomplex, this protein is tightly associated with the thylakoid membrane (PubMed:17468217). Part of the PBS rod (PubMed:16049785, PubMed:17468217, PubMed:31015331). No visible growth phenotype, decreased energy transfer to photosystem I. Decreased accumulation of phycocyanin (PC), but no major effects on the phycobilisome supercomplex. A double cpcG1/cpcG2 deletion has even less PC (PubMed:16049785, PubMed:17468217). No change in state 2 to state 1 transitions (i.e. energy transfer to PSII) (PubMed:19152018). Belongs to the phycobilisome linker protein family.