| Type: | Domain | Name: | GAF domain-like |
| Description: | This entry represents the GAF domain and domains sharing protein structural similarity, such as the C-terminal domain of the transcription regulator IclR, the C-terminal domain of the heat-inducible transcription repressor HrcA, and the phytochrome chromophore attachment domain.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 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-regulate 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 []. | Short Name: | GAF_dom-like |
