Beta subunits of phycoerythrin and phycoerythrocyanin; phycobilisome rod components
phycobilisomes (PBSs) are the main light-harvesting complex in cyanobacteria and red algae. In general, they consist of a central core and surrounding rods and function to harvest and channel light energy toward the photosynthetic reaction centers within the membrane. They are comprised of phycobiliproteins/chromophorylated proteins (PBPs) maintained together by linker polypeptides. PBPs have different numbers of chromophores, and the basic monomer component (alpha/beta heterodimers) can further oligomerize to ring-shaped trimers (heterohexamers) and hexamers (heterododecamers). Stacked PBP hexamers form both the core and the rods of the PBS; the core is mainly made up by allophycocyanin (APC) while the rods can be composed of the PBPs phycoerythrin (PE), phycocyanin (PC) and phycoerythrocyanin (PEC).
Feature 1:chromophore binding site 1 [chemical binding site]
Evidence:
Comment:There are two conserved chromophore binding sites in this subfamily, one located around position Cys-84 and the other at position Cys-153. This binding site represents the former.
Structure:1KTP: Thermosynechococcus vulcanus C-phycocyanin beta binds phycocyanobilin at position Cys-84; contacts at 4A
Comment:Conserved attachment site (Cys-84) present in cyanobacterial and red algal phycobiliproteins, and in the beta-subunits of cryptophyte biliproteins. The actual position of the central conserved Cys varies from positions 81 to 84.
Jiyao W et al.(2023). "The conserved domain database in 2023.",