Dimethoxyethane forms chelate complexes with cations and acts as a bidentate ligand. CD135 is the receptor for the cytokine Flt3 ligand (FLT3L). Where formula 3 is the fraction of receptor bound by the ligand. Affinity is a measure of the tendency of a ligand to bind to its receptor. Sperm find the eggs via chemotaxis, a type of ligand/receptor interaction. Glycine functions as a bidentate ligand for many metal ions. Klotho is an enzyme which effects a receptor to recognize the ligand (FGF23). Ethylene is a fundamental ligand in transition metal alkene complexes. Hyponitrite can act as a bridging or chelating bidentate ligand. After binding to the ligand (steroid hormone), steroid receptors often form dimers. TRPM8 can also be activated by the binding of an extracellular ligand. In the presence of an imidazole ligand, this ferrous complex reversibly binds O. Ammonia can act as a ligand in transition metal complexes. The iron is tethered to the protein via a cysteine thiolate ligand. Dll4 is a transmembrane ligand, for the notch family of receptors.