GAF

Domain present in phytochromes and cGMP-specific phosphodiesterases.
GAF
SMART accession number:SM00065
Description: Mutations within these domains in PDE6B result in autosomal recessive inheritance of retinitis pigmentosa.
Interpro abstract (IPR003018):

The GAF domain is named after some of the proteins it is found in, including cGMP-specific phosphodiesterases, adenylyl cyclases and FhlA. It is also found in and guanylyl cyclases and phytochromes [(PUBMED:9433123), (PUBMED:20004158)]. The structure of a GAF domain shows that the domain shares a similar fold with the PAS domain [(PUBMED:11032796)]. 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 [(PUBMED:20298248)].

The GAF domain is also found in FhlA (formate hydrogen lyase transcriptional activator) and NifA, a transcriptional activator required for activation of most Nif operons, which are directly involved in nitrogen fixation. NifA interacts with sigma-54 [(PUBMED:1404379)].

GO function:protein binding (GO:0005515)
Family alignment:
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There are 56006 GAF domains in 49068 proteins in SMART's nrdb database.

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