ligand-binding domain of membrane guanylyl cyclases (GC-D, GC-E, and GC-F) that are specifically expressed in sensory tissues
This group includes the ligand-binding domain of membrane guanylyl cyclases (GC-D, GC-E, and GC-F) that are specifically expressed in sensory tissues. They share a similar topology with an N-terminal extracellular ligand-binding domain, a single transmembrane domain, and a C-terminal cytosolic region that contains kinase-like and catalytic domains. GC-D is specifically expressed in a subpopulation of olfactory sensory neurons. GC-E and GC-F are colocalized within the same photoreceptor cells of the retina and have important roles in phototransduction. Unlike the other family members, GC-E and GC-F have no known extracellular ligands. Instead, they are activated under low calcium conditions by guanylyl cyclase activating proteins called GCAPs. GC-D expressing neurons have been implicated in pheromone detection and GC-D is phylogenetically more similar to the Ca2+-regulated GC-E and GC-F than to receptor GC-A, -B and -C which are activated by peptide ligands. Moreover, these olfactory GCs and retinal GCs share characteristic sequence similarity in a regulatory domain that is involved in the binding of GCAPs, suggesting GC-D activity may be regulated by an unknown extracellular ligand and intracellular Ca2+. Rodent GC-D-expressing neurons have been implicated in pheromone detection and were recently shown to respond to atmospheric CO2 which is an olfactory stimulus for many invertebrates and regulates some insect innate behavior, such as the location of food and hosts.
Jiyao W et al.(2023). "The conserved domain database in 2023.",