Annotations: 4XB4

Domain Annotation: ECOD Classification ECOD Database Homepage

Chains	Family Name	Domain Identifier	Architecture	Possible Homology	Homology	Topology	Family	Provenance Source (Version)
A	Carot_N	e4xb4A1	A: alpha arrays	X: Orange carotenoid protein, N-terminal domain (From Topology)	H: Orange carotenoid protein, N-terminal domain (From Topology)	T: Orange carotenoid protein, N-terminal domain	F: Carot_N	ECOD (1.6)
B	Carot_N	e4xb4B1	A: alpha arrays	X: Orange carotenoid protein, N-terminal domain (From Topology)	H: Orange carotenoid protein, N-terminal domain (From Topology)	T: Orange carotenoid protein, N-terminal domain	F: Carot_N	ECOD (1.6)

Domain Annotation: CATH CATH Database Homepage

Chain	Domain	Class	Architecture	Topology	Homology	Provenance Source (Version)
A	1.10.2090.10	Mainly Alpha	Orthogonal Bundle	orange carotenoid protein, domain 2	Orange carotenoid-binding protein, N-terminal domain	CATH (4.3.0)
B	1.10.2090.10	Mainly Alpha	Orthogonal Bundle	orange carotenoid protein, domain 2	Orange carotenoid-binding protein, N-terminal domain	CATH (4.3.0)

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
A, B	PF09150	Orange carotenoid protein, N-terminal (Carot_N)	Orange carotenoid protein, N-terminal	Members of this family adopt an alpha-helical structure consisting of two four-helix bundles. They are predominantly found in prokaryotic orange carotenoid protein, and carotenoid binding proteins [1].	Domain

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
A, B	Orange carotenoid-binding protein	molecular transducer activity photoreceptor activity signaling receptor activity ion binding binding anion binding chloride ion binding small molecule binding	detection of light stimulus response to light stimulus detection of external stimulus response to stimulus response to external stimulus detection of abiotic stimulus detection of stimulus light absorption response to abiotic stimulus response to radiation cellular process	intracellular anatomical structure plasma membrane-derived chromatophore membrane membrane plasma membrane intracellular membraneless organelle plasma membrane-derived chromatophore thylakoid membrane intracellular organelle cell periphery cellular anatomical structure plasma membrane-derived thylakoid membrane organelle membraneless organelle plasma membrane region intracellular anatomical structure plasma membrane-derived chromatophore membrane membrane plasma membrane intracellular membraneless organelle plasma membrane-derived chromatophore thylakoid membrane intracellular organelle cell periphery cellular anatomical structure plasma membrane-derived thylakoid membrane organelle membraneless organelle plasma membrane region bacterial thylakoid cytoplasm photosynthetic membrane thylakoid protein-containing complex membrane protein complex light-harvesting complex phycobilisome

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
A, B	IPR015233	Orange carotenoid-binding protein, N-terminal	Domain
A, B	IPR032710	NTF2-like domain superfamily	Homologous Superfamily
A, B	IPR002075	Nuclear transport factor 2 domain	Domain
A, B	IPR036917	Orange carotenoid-binding protein, N-terminal domain superfamily	Homologous Superfamily

RCSB PDB Core Operations are funded by the U.S. National Science Foundation (DBI-2321666), the US Department of Energy (DE-SC0019749), and the National Cancer Institute, National Institute of Allergy and Infectious Diseases, and National Institute of General Medical Sciences of the National Institutes of Health under grant R01GM157729.