Skip to main content
. 2023 Jun 6;14:3284. doi: 10.1038/s41467-023-39030-2

Fig. 1. An overview of the monoamine system.

Fig. 1

A Synthesis pathways for key monoamines including the substrate, chemical modification, enzymes, and products. Arrows indicate reactions with the facilitating enzyme overlain. For each enzyme, the label shows the name while the colour indicates the gene family. Chemical modifications are shown next to the enzymes responsible. B Cartoon of a synapse with the different enzymes required for the production and detection of monoamines. The red circles represent monoamines and precursor molecules. Yellow squares represent tetrahydrobiopterin co-factor. C Current molecular evidence from the literature supporting the presence of monoamines outside Bilaterians in the literature. Dark grey indicates positive results, light grey displays uncertain or partial evidence (e.g., precursors, related compounds) and an X indicates negative results. Blank shapes indicate a lack of evidence. Staining refers to any chemical or immuno-staining experiments; pharmacology refers to evidence-based drug perturbations, adding inhibitors or other chemical interference experiments; HPLC High-Pressure Liquid Chromatography (see Supplementary Data 1 for references and details). PAH phenylalanine hydroxylase, TPH tryptophan hydroxylase, TH tyrosine hydroxylase, DDC dopa decarboxylase, TDC tyrosine decarboxylase, HDC histidine decarboxylase, DBH dopamine beta hydroxylase, TBH tyramine beta hydroxylase, PNMT phenylethanolamine-N-methyltransferase, AAAH aromatic amino acid decarboxylase, AADC aromatic amine decarboxylase, BH beta hydroxylase, VMAT vesicular monoamine transporter, GCH GTP cyclo-hydrolase, GPCR g-protein coupled receptor, LGIC ligand gated ion channel, SLC solute ligand carrier, MAO monoamine oxidase. (A) and (B) were made with Biorender. Silhouettes obtained from Phylopic.org. Silhouette images are by Christoph Schomburg (Dendronephthya gigantea); Daniel Jaron (Mus musculus); Emily Jane McTavish, from http://chestofbooks.com/animals/Manual-Of-Zoology/images/I-Order-Ciliata-41.jpg (Ciliophora); Konsta Happonen, from a CC-BY-NC image by sokolkov 2002 on iNaturalist (Geranium sylvaticum); Mali’o Kodis, photograph by Ching (http://www.flickr.com/photos/36302473@N03/) (Chrysaora fuscescens); Noah Schlottman (Pleurobrachia); Oliver Voigt (Trichoplax adhaerens); Steven Traver (Hydra); and Tess Linden (Salpingoeca rosetta).