Catalyzes the site-selective attachment of phycocyanobilin (PCB) to 'Cys-154' of C-phycocyanin subunit beta (CpcB) and to 'Cys-153' of phycoerythrocyanin subunit beta (PecB). Does not have chromophore lyase activity for ApcA1, ApcA2, ApcB, ApcD, ApcF or PecA. Constitutively expressed. Belongs to the CpcT/CpeT biliprotein lyase family.