Leptin receptor (OB-R) is a type I cytokine receptor family protein with significant amino acid sequence identity with gp130, G-CSF receptor, and LIF receptor. An OB-R transcript encodes a soluble form of the receptor. The transcript was reported to be expressed predominantly in regions of the hypothalamus previously thought to be important in body weight regulation. OB-R binds leptin with high affinity and is a potent leptin antagonist. Human OB-R encodes a 1 165 amino acid residue precursor protein with a 22 amino acid residue signal peptide, an 816 amino acid residue extracellular domain, a 21 amino acid residue transmembrane domain and a 303 amino acid residue cytoplasmic domain.