The enzyme, characterized from the cyanobacterium Microchaete diplosiphon, catalyses the attachment of the phycobilin chromophore (3E)-phycoerythrobilin (PEB) to cysteine 82 of the alpha subunit of the phycobiliprotein C-phycoerythrin. The numbering used here corresponds to the enzyme from Microchaete diplosiphon, and could vary slightly in other organisms. Activity is greatly enhanced in the presence of the chaperone-like protein CpeZ. The reaction could also be catalysed by EC 4.4.1.29, phycobiliprotein cysteine-84 phycobilin lyase, but much less efficiently.
