Acts as a chromphore lyase, covalently attaching 3Z-phycoerythrobilin (3Z-PEB) to its target protein CpeB (phycoerythrin). Binds the isomeric chromophores 3E-phycoerythrobilin (3E-PEB), 3Z-PEB as well as their precursor 15,16-dihydrobiliverdin (DHBV) but not other chromophores tested. While it can transfer 3E-PEB a non-physiological adduct is made. Chromophore is bound to the lyase in a ratio of nearly 1:1. Homodimer. Belongs to the CpcS/CpeS biliprotein lyase family.