| Type: | Domain | Name: | GAF domain |
| 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 [, ]. The structure of a GAF domain shows that the domain shares a similar fold with the PAS domain []. 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 [].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 []. | Short Name: | GAF |
| DB identifier | Type | Name |
|---|---|---|
| IPR001294 | Family | Phytochrome |
| IPR014525 | Family | Signal transduction histidine kinase, hybrid-type, ethylene sensor |
| IPR014265 | Family | Signal transduction histidine kinase, PEP-CTERM system, putative |
| IPR010113 | Family | Nif-specific regulatory protein |
| IPR012074 | Family | GAF-ANTAR transcription anti-termination regulator, putative |
