Lipocalin-type prostaglandin D synthase (L-PGDS; EC:5.3.99.2) is a secreted enzyme and the second most abundant protein in human cerebrospinal fluid. L-PGDS acts as both, an enzyme and as a lipid transporter, converting prostaglandin H2 to prostaglandin D2 and serving as a carrier for hydrophobic ligands including retinoids, hemoglobin metabolites, thyroid hormones, gangliosides, and fatty acids. L-PGDS belongs to the lipocalin/cytosolic fatty-acid binding protein family which has a large beta-barrel ligand-binding cavity. Lipocalins are mainly low molecular weight extracellular proteins that bind principally small hydrophobic ligands, and form covalent or non-covalent complexes with soluble macromolecules, as well as membrane bound-receptors. They participate in processes such as ligand transport, modulation of cell growth and metabolism, regulation of immune response, smell reception, tissue development and animal behavior. Cytosolic fatty-acid binding proteins, also bind hydrophobic ligands in a non-covalent, reversible manner, and have been implicated in intracellular uptake, transport and storage of hydrophobic ligands, regulation of lipid metabolism and sequestration of excess toxic fatty acids, as well as in signaling, gene expression, inflammation, cell growth and proliferation, and cancer development.
Comment:hydrophobic cavity binds different hydrophobic ligands; ligands are bound within the beta-barrel in a central internal water-filled cavity lined with polar and hydrophobic amino acids
Jiyao W et al.(2023). "The conserved domain database in 2023.",