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. Has intrinsic bilin lyase activity. 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 three minor components: the allophycocyanin alpha-B chain, a 18.3 kDa polypeptide, and the anchor polypeptide L-CM. Anchors the phycobilisome perpendicularly to the cytoplasmic surface of the thylakoid membrane. Contains one covalently linked bilin chromophore. This protein autochromophorylates (By similarity). Belongs to the phycobilisome linker protein family.