UniProt functional annotation for P74102



	UniProt functional annotation for P74102

UniProt code: P74102.

Organism: Synechocystis sp. (strain PCC 6803 / Kazusa).

Taxonomy: Bacteria; Cyanobacteria; Synechococcales; Merismopediaceae; Synechocystis; unclassified Synechocystis.

Function: Acts as a blue-light photoreceptor and photo-protectant. Essential for inhibiting damaged induced by excess blue-green light via a process known as non-photochemical quenching (NPQ) (PubMed:16531492, PubMed:18687902, PubMed:20368334). In the dark or dim light the stable inactive form (OCP-O) is orange, upon illumination with blue-green light it converts to a metastable active red form (OCP-R), inducing energy dissipation, quenching cellular fluorescence via NPQ (PubMed:18687902, PubMed:20368334). One OCP-R molecule is sufficient to quench 1 phycobilisome (PubMed:21764991). More OCP-R accumulates under high-light and low temperature; in the dark OCP-R spontaneously reverts to OCP-O (PubMed:18687902). Reversion of OCP-O is accelerated by FRP (PubMed:20534537, PubMed:23716688). A kinetic study suggests conversion of OCP-O to OCP-R is limited by cis-trans proline isomerization of either Gln224-Pro225 or Pro225-Pro226 (PubMed:21907180). {ECO:0000269|PubMed:16531492, ECO:0000269|PubMed:18687902, ECO:0000269|PubMed:20368334, ECO:0000269|PubMed:20534537, ECO:0000269|PubMed:21764991, ECO:0000269|PubMed:21907180, ECO:0000269|PubMed:23716688}.

Cofactor: Name=3'-hydroxyechinenone; Xref=ChEBI:CHEBI:80214; Evidence={ECO:0000269|PubMed:18687902, ECO:0000269|PubMed:20368334}; Note=Binds 1 carotenoid molecule per subunit (3'-hydroxyechinenone is the physiological carotenoid, echinenone (70%), 3'-hydroxyechinenone (16%) or zeaxanthin (14%) were all detected in overexpressed, crystallized protein), makes contacts with both domains of the whole protein (PubMed:20368334). Upon RCP generation the carotenoid translocates 12 Angstroms into the N-terminal domain, altering its binding and photochemical properties (PubMed:26113721). {ECO:0000269|PubMed:20368334, ECO:0000269|PubMed:26113721};

Biophysicochemical properties: Absorption: Abs(max)=~495 nm; Note=A double maxima at 467 and 495 nm is seen for the orange (inactive) form, the red (active) form has a single maximum at ~505 nm. {ECO:0000269|PubMed:18687902, ECO:0000269|PubMed:20368334};

Subunit: Monomer (PubMed:20368334). Interacts with the APC core of the phycobilisome (PB), probably at a ratio of 1:1 in a light-independent manner; possibly only OCP-R binds to PBs. Interacts with FRP (PubMed:20534537, PubMed:23716688). Detachment from PBs is accelerated by FPR (PubMed:21764991). {ECO:0000269|PubMed:20368334, ECO:0000269|PubMed:20534537, ECO:0000269|PubMed:21764991, ECO:0000269|PubMed:23716688}.

Subcellular location: Cellular thylakoid membrane {ECO:0000269|PubMed:16531492}; Peripheral membrane protein {ECO:0000305}; Cytoplasmic side {ECO:0000269|PubMed:16531492}. Note=Associated with the phycobilisome on the cytoplasmic side of the thylakoid membrane (PubMed:16531492). {ECO:0000269|PubMed:16531492}.

Induction: Transcribed from its own promoter, it may also be cotranscribed with downstream frp. {ECO:0000269|PubMed:20534537}.

Domain: Binds FRP via the C-terminal domain (residues 170-317) (PubMed:23716688). Upon RCP generation the carotenoid translocates 12 Angstroms into the N-terminal domain, altering its binding and photochemical properties (PubMed:26113721). {ECO:0000269|PubMed:23716688, ECO:0000269|PubMed:26113721}.

Ptm: Proteolytically cleaved into a red 16.7 kDa form named red carotenoid-binding protein (RCP) which lacks 15 residues from the N- terminus and approximately 150 residues from the C-terminus (PubMed:9398074). {ECO:0000269|PubMed:9398074}.

Mass spectrometry: [Orange carotenoid-binding protein]: Mass=34622; Method=MALDI; Note=OCP.; Evidence={ECO:0000269|PubMed:9398074};

Mass spectrometry: [Red carotenoid-binding protein]: Mass=16739; Method=MALDI; Note=RCP.; Evidence={ECO:0000269|PubMed:9398074};

Disruption phenotype: Loss of NPQ induced by strong white or blue-green light, cells are more sensitive to high light. {ECO:0000269|PubMed:16531492}.

Similarity: Belongs to the orange carotenoid-binding protein family. {ECO:0000255|PROSITE-ProRule:PRU01109, ECO:0000305}.

Annotations taken from UniProtKB at the EBI.


Organism:		Synechocystis sp. (strain PCC 6803 / Kazusa).
Taxonomy:		Bacteria; Cyanobacteria; Synechococcales; Merismopediaceae; Synechocystis; unclassified Synechocystis.



Function:		Acts as a blue-light photoreceptor and photo-protectant. Essential for inhibiting damaged induced by excess blue-green light via a process known as non-photochemical quenching (NPQ) (PubMed:16531492, PubMed:18687902, PubMed:20368334). In the dark or dim light the stable inactive form (OCP-O) is orange, upon illumination with blue-green light it converts to a metastable active red form (OCP-R), inducing energy dissipation, quenching cellular fluorescence via NPQ (PubMed:18687902, PubMed:20368334). One OCP-R molecule is sufficient to quench 1 phycobilisome (PubMed:21764991). More OCP-R accumulates under high-light and low temperature; in the dark OCP-R spontaneously reverts to OCP-O (PubMed:18687902). Reversion of OCP-O is accelerated by FRP (PubMed:20534537, PubMed:23716688). A kinetic study suggests conversion of OCP-O to OCP-R is limited by cis-trans proline isomerization of either Gln224-Pro225 or Pro225-Pro226 (PubMed:21907180). {ECO:0000269\|PubMed:16531492, ECO:0000269\|PubMed:18687902, ECO:0000269\|PubMed:20368334, ECO:0000269\|PubMed:20534537, ECO:0000269\|PubMed:21764991, ECO:0000269\|PubMed:21907180, ECO:0000269\|PubMed:23716688}.


Cofactor:		Name=3'-hydroxyechinenone; Xref=ChEBI:CHEBI:80214; Evidence={ECO:0000269\|PubMed:18687902, ECO:0000269\|PubMed:20368334}; Note=Binds 1 carotenoid molecule per subunit (3'-hydroxyechinenone is the physiological carotenoid, echinenone (70%), 3'-hydroxyechinenone (16%) or zeaxanthin (14%) were all detected in overexpressed, crystallized protein), makes contacts with both domains of the whole protein (PubMed:20368334). Upon RCP generation the carotenoid translocates 12 Angstroms into the N-terminal domain, altering its binding and photochemical properties (PubMed:26113721). {ECO:0000269\|PubMed:20368334, ECO:0000269\|PubMed:26113721};
Biophysicochemical properties:		Absorption: Abs(max)=~495 nm; Note=A double maxima at 467 and 495 nm is seen for the orange (inactive) form, the red (active) form has a single maximum at ~505 nm. {ECO:0000269\|PubMed:18687902, ECO:0000269\|PubMed:20368334};
Subunit:		Monomer (PubMed:20368334). Interacts with the APC core of the phycobilisome (PB), probably at a ratio of 1:1 in a light-independent manner; possibly only OCP-R binds to PBs. Interacts with FRP (PubMed:20534537, PubMed:23716688). Detachment from PBs is accelerated by FPR (PubMed:21764991). {ECO:0000269\|PubMed:20368334, ECO:0000269\|PubMed:20534537, ECO:0000269\|PubMed:21764991, ECO:0000269\|PubMed:23716688}.
Subcellular location:		Cellular thylakoid membrane {ECO:0000269\|PubMed:16531492}; Peripheral membrane protein {ECO:0000305}; Cytoplasmic side {ECO:0000269\|PubMed:16531492}. Note=Associated with the phycobilisome on the cytoplasmic side of the thylakoid membrane (PubMed:16531492). {ECO:0000269\|PubMed:16531492}.
Induction:		Transcribed from its own promoter, it may also be cotranscribed with downstream frp. {ECO:0000269\|PubMed:20534537}.
Domain:		Binds FRP via the C-terminal domain (residues 170-317) (PubMed:23716688). Upon RCP generation the carotenoid translocates 12 Angstroms into the N-terminal domain, altering its binding and photochemical properties (PubMed:26113721). {ECO:0000269\|PubMed:23716688, ECO:0000269\|PubMed:26113721}.
Ptm:		Proteolytically cleaved into a red 16.7 kDa form named red carotenoid-binding protein (RCP) which lacks 15 residues from the N- terminus and approximately 150 residues from the C-terminus (PubMed:9398074). {ECO:0000269\|PubMed:9398074}.
Mass spectrometry:		[Orange carotenoid-binding protein]: Mass=34622; Method=MALDI; Note=OCP.; Evidence={ECO:0000269\|PubMed:9398074};
Mass spectrometry:		[Red carotenoid-binding protein]: Mass=16739; Method=MALDI; Note=RCP.; Evidence={ECO:0000269\|PubMed:9398074};
Disruption phenotype:		Loss of NPQ induced by strong white or blue-green light, cells are more sensitive to high light. {ECO:0000269\|PubMed:16531492}.
Similarity:		Belongs to the orange carotenoid-binding protein family. {ECO:0000255\|PROSITE-ProRule:PRU01109, ECO:0000305}.