Annotations: 9ER4

Protein Family Annotation Pfam Database Homepage

Chains	Accession	Name	Description	Comments	Source
A, B	PF01590	GAF domain (GAF)	GAF domain	This domain is present in cGMP-specific phosphodiesterases, adenylyl and guanylyl cyclases, phytochromes, FhlA and NifA. Adenylyl and guanylyl cyclases catalyse ATP and GTP to the second messengers cAMP and cGMP, respectively, these products up-regul ...	This domain is present in cGMP-specific phosphodiesterases, adenylyl and guanylyl cyclases, phytochromes, FhlA and NifA. Adenylyl and guanylyl cyclases catalyse ATP and GTP to the second messengers cAMP and cGMP, respectively, these products up-regulating catalytic activity by binding to the regulatory GAF domain(s). The opposite hydrolysis reaction is catalysed by phosphodiesterase. cGMP-dependent 3',5'-cyclic phosphodiesterase catalyses the conversion of guanosine 3',5'-cyclic phosphate to guanosine 5'-phosphate. Here too, cGMP regulates catalytic activity by GAF-domain binding. Phytochromes are regulatory photoreceptors in plants and bacteria which exist in two thermally-stable states that are reversibly inter-convertible by light: the Pr state absorbs maximally in the red region of the spectrum, while the Pfr state absorbs maximally in the far-red region. This domain is also found in FhlA (formate hydrogen lyase transcriptional activator) and NifA, a transcriptional activator which is required for activation of most Nif operons which are directly involved in nitrogen fixation. NifA interacts with sigma-54. This domain can bind biliverdine and phycocyanobilin (Matilla et al., FEMS Microbiology Reviews, fuab043, 45, 2021, 1. https://doi.org/10.1093/femsre/fuab043).	Domain
A, B	PF08446	PAS fold (PAS_2)	PAS fold	The PAS fold corresponds to the structural domain that has previously been defined as PAS and PAC motifs [4]. The PAS fold appears in archaea, eubacteria and eukarya.	Domain

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
A, B	Phytochrome A-2	identical protein binding protein binding binding protein homodimerization activity protein dimerization activity molecular sensor activity catalytic activity, acting on a protein kinase activity protein kinase activity transferase activity phosphotransferase activity, nitrogenous group as acceptor phosphotransferase activity, alcohol group as acceptor protein histidine kinase activity transferase activity, transferring phosphorus-containing groups identical protein binding protein binding binding protein homodimerization activity protein dimerization activity molecular sensor activity catalytic activity, acting on a protein kinase activity protein kinase activity transferase activity phosphotransferase activity, nitrogenous group as acceptor phosphotransferase activity, alcohol group as acceptor protein histidine kinase activity transferase activity, transferring phosphorus-containing groups phosphorelay sensor kinase activity molecular function regulator activity catalytic activity molecular transducer activity photoreceptor activity signaling receptor activity	regulation of cellular process RNA metabolic process regulation of primary metabolic process nucleobase-containing compound metabolic process RNA biosynthetic process nucleic acid biosynthetic process DNA-templated transcription regulation of RNA metabolic process regulation of nucleobase-containing compound metabolic process regulation of RNA biosynthetic process regulation of biosynthetic process regulation of biological process biological regulation primary metabolic process regulation of cellular process RNA metabolic process regulation of primary metabolic process nucleobase-containing compound metabolic process RNA biosynthetic process nucleic acid biosynthetic process DNA-templated transcription regulation of RNA metabolic process regulation of nucleobase-containing compound metabolic process regulation of RNA biosynthetic process regulation of biosynthetic process regulation of biological process biological regulation primary metabolic process regulation of macromolecule metabolic process nucleobase-containing compound biosynthetic process gene expression macromolecule biosynthetic process nucleic acid metabolic process regulation of gene expression biosynthetic process cellular process metabolic process regulation of macromolecule biosynthetic process regulation of DNA-templated transcription macromolecule metabolic process regulation of metabolic process cellular response to stimulus response to light stimulus cellular response to red or far red light response to stimulus signaling response to red or far red light detection of abiotic stimulus cell communication cellular response to environmental stimulus cellular response to light stimulus signal transduction phototransduction detection of light stimulus detection of external stimulus red or far-red light signaling pathway response to external stimulus cellular response to radiation detection of stimulus red, far-red light phototransduction response to radiation response to abiotic stimulus cellular response to abiotic stimulus protein-tetrapyrrole linkage macromolecule modification protein-phycocyanobilin linkage protein metabolic process protein modification process protein-bilin linkage detection of visible light	membrane-bounded organelle intracellular organelle cellular anatomical structure intracellular anatomical structure organelle nucleus intracellular membrane-bounded organelle

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
A, B	IPR013767	PAS fold	Domain
A, B	IPR013515	Phytochrome, central region	Domain
A, B	IPR000014	PAS domain	Domain
A, B	IPR012129	Phytochrome A/B/C/D/E	Family
A, B	IPR043150	Phytochrome, PHY domain superfamily	Homologous Superfamily
A, B	IPR036890	Histidine kinase/HSP90-like ATPase superfamily	Homologous Superfamily
A, B	IPR003661	Signal transduction histidine kinase, dimerisation/phosphoacceptor domain	Domain
A, B	IPR013654	PAS fold-2	Domain
A, B	IPR035965	PAS domain superfamily	Homologous Superfamily
A, B	IPR000700	PAS-associated, C-terminal	Domain
A, B	IPR013516	Phytochrome chromophore binding site	Binding Site
A, B	IPR005467	Histidine kinase domain	Domain
A, B	IPR003018	GAF domain	Domain
A, B	IPR029016	GAF-like domain superfamily	Homologous Superfamily
A, B	IPR001294	Phytochrome	Family
A, B	IPR016132	Phytochrome chromophore attachment domain	Domain

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.