Fig. 3. Domain architecture of human SLCO5A1.

a Schematic representation of the protein with the indication of recognised domains. A SMART analysis to identify structural domains confirmed the presence of two modules, Major Facilitator Superfamily (MFS) and a Kazal domain, interspaced with potentially unstructured sequences. The MFS transporters are membrane proteins capable of transporting small solutes in response to chemiosmotic ion gradients^72,73. They are represented in many organisms from Archaea to Homo sapiens. MFS proteins target a wide range of substrates, including ions, carbohydrates, lipids, amino acids and peptides, nucleosides and other small molecules and transport them in both directions across the membrane⁷⁴. The Kazal domain is an evolutionary conserved module usually acting as a serine-protease inhibitor. b Predicted model of the monomeric form of SLCO5A1 from amino acids 115–766, built using the SwissModel homology server (https://swissmodel.expasy.org) and utilising the template structure pdb:7eeb. Red: alpha helices; Yellow: Beta strands; Green: Loops.