Beta-Lactoglobulin (beta-LG) is the major whey protein of ruminant species and present in the milk of many other species, with a notable exception of human. It is the major allergen of bovine milk. Beta-LG has been shown to bind hydrophobic ligands such as curcumin, vitamin E or fatty acids, or hydrophilic such as vitamin B9. This group also includes human glycodelin (also known as placental protein 14, pregnancy-associated endometrial alpha-2 globulin, and progestagen-associated endometrial protein) which is involved in crucial biological processes such as reproduction and immune reaction. Four glycoforms of glycodelin have been identified in reproductive tissue that differ in glycosylation and biological activity. This group belongs to the lipocalin/cytosolic fatty-acid binding protein family which have 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.",