Characterized or predicted function of phycobilin lyases

This table lists the characterized (roman) or predicted (italics) function of phycobilin lyases in vivo, in terms of their:

chromophore bound: phycocyanobilin (PCB) or phycoerythrobilin (PEB)
enzymatic activity: lyase or lyase-isomerase. Note that a PCB lyase-isomerase will bind a PCB and isomerize it into phycoviolibilin (PVB) and that a PEB lyase-isomerase will bind a PEB and isomerize it into phycourobilin (PUB).
Substrate: apoprotein targeted by the enzyme
Cysteinyl binding sites: positions where chromophores are bound. Numbers in the table correspond to consensus numbering (Scheer et al., 2008). Note that marine Synechococcus for instance generally have different positions than indicated (i.e. Cys-81 on all APC subunits; Cys-82 and 153 on CpcB/RpcB; Cys-82 and 139 on CpeA; Cys-50/61, 82 and 165 on CpeB).

It is worth noting that many phycobilin lyases have a broader enzymatic activity in vitro, i.e. in heterologous, multi-plasmid expression systems in Escherichia coli (see e.g. Blot et al., 2009).

Phycobiliprotein	Allophycocyanin				Phycocyanin			Phycoerythrocyanin			Phycoerythrin I						Phycoerythrin II							Phycoerythrin III
Apoprotein name	ApcA	ApcB	ApcD	ApcF	CpcA/RpcA	CpcB/RpcB	CpcB/RpcB	PecA	PecB	PecB	CpeA	CpeA	CpeB	CpeB	CpeB	-	MpeA	MpeA	MpeA	MpeB	MpeB	MpeB	-	PpeA	PpeB	PpeB	PpeB	-
Consensus binding site	α-82	β-82	αB-82	β18-82	α-84	β-84	β-155	α-84	β-84	β-155	α-84	a-143	β-50/61	β-84	β-155	unknown	α-75	α-83	α-140	β-50/61	β-82	β-159	unknown	α-73	β-61	β-82	β-163	unknown
Function	α-82	β-82	αB-82	β18-82	α-84	β-84	β-155	α-84	β-84	β-155	α-84	a-143	β-50/61	β-84	β-155	unknown	α-75	α-83	α-140	β-50/61	β-82	β-159	unknown	α-73	β-61	β-82	β-163	unknown
PCB lyase	CpcS-I + CpcU-I CpcS-II + CpcU-II ? CpcS-III	CpcS-I + CpcU-I CpcS-II + CpcU-II ? CpcS-III	CpcS-I + CpcU-I CpcS-II + CpcU-II ? CpcS-III	CpcS-I + CpcU-I CpcS-II + CpcU-II ? CpcS-III	CpcE-I + CpcF-I CpcE-II + CpcF-II ?	CpcS-I + CpcU-I CpcS-II + CpcU-II ? CpcS-III	CpcT		CpcS-III	CpcT
PEB lyase					RpcE + RpcF ?		RpcT ?				CpeY + CpeZ		CpeF	CpeS-I CpeS-II ?	CpeT	CpeU ?		CpeY + CpeZ ?		CpeF ?	CpeS-II ?	CpeT ?	MpeU ?	CpeY + CpeZ ?	CpeF ?	CpeS-II ? CpeS-ProHL	CpeT ?
PCB lyase-isomerase								PecE + PecF
PEB lyase-isomerase					RpcG							Unknown PEB lyase or lyase-isomerase ?	Unknown PEB lyase or lyase-isomerase ?				Unknown PEB lyase or lyase-isomerase ?	MpeY ? MpeZ MpeW ?	Unknown PEB lyase or lyase-isomerase ?	Unknown PEB lyase or lyase-isomerase ?