Domain

GAF domain (IPR003018)

Short name: GAF

Domain relationships

Description

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 [PMID: 9433123, PMID: 20004158]. The structure of a GAF domain shows that the domain shares a similar fold with the PAS domain [PMID: 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 [PMID: 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 [PMID: 1404379].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0005515 protein binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
Pfam
SMART
Pfam
Pfam