Catalytic domain of Phototropin-like Serine/Threonine Kinases
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. Phototropins are blue-light receptors that control responses such as phototropism, stromatal opening, and chloroplast movement in order to optimize the photosynthetic efficiency of plants. They are light-activated STKs that contain an N-terminal photosensory domain and a C-terminal catalytic domain. The N-terminal domain contains two LOV (Light, Oxygen or Voltage) domains that binds FMN. Photoexcitation of the LOV domains results in autophosphorylation at multiple sites and activation of the catalytic domain. In addition to plant phototropins, included in this subfamily are predominantly uncharacterized fungal STKs whose catalytic domains resemble the phototropin kinase domain. One protein from Neurospora crassa is called nrc-2, which plays a role in growth and development by controlling entry into the conidiation program. The phototropin-like subfamily is part of a larger superfamily that includes the catalytic domains of other STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.
Jiyao W et al.(2023). "The conserved domain database in 2023.",