IUBMB Enzyme Nomenclature


Accepted name: phycobiliprotein β-cysteine-155 phycobilin lyase

Reaction: (1) [C-phycocyanin β-subunit]-Cys155-phycocyanobilin = apo-[C-phycocyanin β-subunit] + (2R,3E)-phycocyanobilin
(2) [phycoerythrocyanin β-subunit]-Cys155-phycocyanobilin = apo-[phycoerythrocyanin β-subunit] + (2R,3E)-phycocyanobilin

Glossary: phycocyanobilin = 3,31-didehydro-2,3-dihydromesobiliverdin

Other name(s): cpcT (gene name); cpeT1 (gene name); cpcT1 (gene name)

Systematic name: [phycobiliprotein β-subunit]-Cys155-phycocyanobilin:phycocyanobilin lyase

Comments: The enzyme, found in cyanobacteria and red algae, catalyses the attachment of the phycobilin chromophore phycocyanobilin to cysteine 155 of the β subunits of the phycobiliproteins C-phycocyanin and phycoerythrocyanin. The numbering used here corresponds to the enzyme from Anabaena, and could vary slightly in other organisms.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:


1. Zhao, K.H., Zhang, J., Tu, J.M., Bohm, S., Ploscher, M., Eichacker, L., Bubenzer, C., Scheer, H., Wang, X. and Zhou, M. Lyase activities of CpcS- and CpcT-like proteins from Nostoc PCC7120 and sequential reconstitution of binding sites of phycoerythrocyanin and phycocyanin β-subunits. J. Biol. Chem. 282 (2007) 34093-34103. [PMID: 17895251]

2. Zhang, R., Feng, X.T., Wu, F., Ding, Y., Zang, X.N., Zhang, X.C., Yuan, D.Y. and Zhao, B.R. Molecular cloning and expression analysis of a new bilin lyase: the cpcT gene encoding a bilin lyase responsible for attachment of phycocyanobilin to Cys-153 on the β-subunit of phycocyanin in Arthrospira platensis FACHB314. Gene 544 (2014) 191-197. [PMID: 24768724]

3. Zhou, W., Ding, W.L., Zeng, X.L., Dong, L.L., Zhao, B., Zhou, M., Scheer, H., Zhao, K.H. and Yang, X. Structure and mechanism of the phycobiliprotein lyase CpcT. J. Biol. Chem. 289 (2014) 26677-26689. [PMID: 25074932]

[EC created 2015]

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