This protein is postulated to act both as terminal energy acceptor (by its phycobilin-like domains) and as a linker polypeptide (by its repeats and arms) that stabilizes the phycobilisome core architecture (By similarity). Has intrinsic bilin lyase activity. Heterodimer with ApcF (a variant beta-allophycocyanin). Phycobilisomes of this organism are composed of a two cylinder core, from which six rods radiate. The core is mainly composed of allophycocyanin alpha and beta chains and of minor components (By similarity). Anchors the phycobilisome perpendicularly to the cytoplasmic surface of the thylakoid membrane. Contains one covalently linked bilin chromophore. This protein autochromophorylates. Belongs to the phycobilisome linker protein family.