P74102 · OCP_SYNY3

Function

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).

Cofactor

3'-hydroxyechinenone (UniProtKB | Rhea| CHEBI:80214 )

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).

Absorption

Abs(max) = ~495nm
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.

Features

Showing features for binding site.

TypeIDPosition(s)Description
Binding site34-38echinenone (UniProtKB | ChEBI); only in form RCP
Binding site37-44echinenone (UniProtKB | ChEBI); in forms OCP and RCP
Binding site80-83echinenone (UniProtKB | ChEBI); only in form RCP
Binding site107-117echinenone (UniProtKB | ChEBI); in forms OCP and RCP
Binding site125-129echinenone (UniProtKB | ChEBI); only in form RCP
Binding site151-161echinenone (UniProtKB | ChEBI); residues alter contact in forms OCP and RCP
Binding site201echinenone (UniProtKB | ChEBI); only in form OCP
Binding site245-250echinenone (UniProtKB | ChEBI); only in form OCP
Binding site273-284echinenone (UniProtKB | ChEBI); only in form OCP
Binding site288echinenone (UniProtKB | ChEBI); only in form OCP

GO annotations

AspectTerm
Cellular Componentphycobilisome
Cellular Componentplasma membrane-derived thylakoid membrane
Molecular Functionchloride ion binding
Molecular Functionphotoreceptor activity
Biological Processlight absorption

Keywords

Names & Taxonomy

Protein names

  • Recommended name
    Orange carotenoid-binding protein
  • Short names
    OCP
  • Cleaved into 1 chains

Gene names

    • Ordered locus names
      slr1963

Organism names

Accessions

  • Primary accession
    P74102

Proteomes

Subcellular Location

Cellular thylakoid membrane
; Peripheral membrane protein
Note: Associated with the phycobilisome on the cytoplasmic side of the thylakoid membrane (PubMed:16531492).

Keywords

Phenotypes & Variants

Disruption phenotype

Loss of NPQ induced by strong white or blue-green light, cells are more sensitive to high light.

Features

Showing features for mutagenesis.

TypeIDPosition(s)Description
Mutagenesis34Alters carotenoid specificity, <40% quenching, decreases stability of OCP-R, accelerates OCP-R to OCP-O reversion.
Mutagenesis44Acts like wild-type.
Mutagenesis44Cannot convert to red form (OCP-R), no NPQ. Does not bind to phycobilisomes.
Mutagenesis84<40% quenching, decreases stability of OCP-R, accelerates OCP-R to OCP-O reversion.
Mutagenesis110Acts like wild-type.
Mutagenesis110Incomplete conversion to red form (OCP-R), no NPQ.
Mutagenesis126<40% quenching, decreases stability of OCP-R, accelerates OCP-R to OCP-O reversion.
Mutagenesis126-129Cannot convert to red form (OCP-R).
Mutagenesis129<40% quenching, decreases stability of OCP-R, accelerates OCP-R to OCP-O reversion.
Mutagenesis155Able to convert to red form (OCP-R), no NPQ.

PTM/Processing

Features

Showing features for initiator methionine, chain.

TypeIDPosition(s)Description
Initiator methionine1Removed
ChainPRO_00002823522-317Orange carotenoid-binding protein
ChainPRO_000028235316-?Red carotenoid-binding protein

Post-translational modification

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).

Proteomic databases

Expression

Induction

Transcribed from its own promoter, it may also be cotranscribed with downstream frp.

Interaction

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).

Binary interactions

TypeEntry 1Entry 2Number of experimentsIntact
BINARY P74102frp P741032EBI-1618104, EBI-1618115

Protein-protein interaction databases

Family & Domains

Features

Showing features for domain.

TypeIDPosition(s)Description
Domain18-169OCP N-terminal

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).

Sequence similarities

Belongs to the orange carotenoid-binding protein family.

Phylogenomic databases

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Length
    317
  • Mass (Da)
    34,659
  • Last updated
    1997-02-01 v1
  • Checksum
    8FF633BDE6D530F2
MPFTIDSARGIFPNTLAADVVPATIARFSQLNAEDQLALIWFAYLEMGKTLTIAAPGAASMQLAENALKEIQAMGPLQQTQAMCDLANRADTPLCRTYASWSPNIKLGFWYRLGELMEQGFVAPIPAGYQLSANANAVLATIQGLESGQQITVLRNAVVDMGFTAGKDGKRIAEPVVPPQDTASRTKVSIEGVTNATVLNYMDNLNANDFDTLIELFTSDGALQPPFQRPIVGKENVLRFFREECQNLKLIPERGVTEPAEDGFTQIKVTGKVQTPWFGGNVGMNIAWRFLLNPEGKIFFVAIDLLASPKELLNFAR

Features

Showing features for sequence conflict.

TypeIDPosition(s)Description
Sequence conflict73in Ref. 1; AA sequence
Sequence conflict75in Ref. 1; AA sequence
Sequence conflict121in Ref. 1; AA sequence
Sequence conflict165in Ref. 1; AA sequence
Sequence conflict169in Ref. 1; AA sequence

Mass Spectrometry

Orange carotenoid-binding protein

Molecular mass is 34,622 Da. Determined by MALDI. OCP.

Red carotenoid-binding protein

Molecular mass is 16,739 Da. Determined by MALDI. RCP.

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
BA000022
EMBL· GenBank· DDBJ
BAA18188.1
EMBL· GenBank· DDBJ
Genomic DNA

Genome annotation databases

Similar Proteins

Disclaimer

Any medical or genetic information present in this entry is provided for research, educational and informational purposes only. It is not in any way intended to be used as a substitute for professional medical advice, diagnosis, treatment or care. Our staff consists of biologists and biochemists that are not trained to give medical advice.
We'd like to inform you that we have updated our Privacy Notice to comply with Europe’s new General Data Protection Regulation (GDPR) that applies since 25 May 2018.
FeedbackHelp