Named leptin (from leptos, Greek for thin) because of its ability to reduce fat stores, the protein shows high interspecies conservation, with mature human leptin being 87% and 84% identical to mouse and rat leptin proteins, respectively. Leptin is frequently also referred to as OB protein, the product of the ob (obese) gene. Human leptin has been found to be active in both the mouse and rat systems. The expression of leptin is very limited and has been found only in adipocytes. A mutation in the ob gene has been found in mice, but not in humans. This mutation results in a mature, non-functional, 81 aa residue, truncated leptin that contributes to the general obesity associated with the ob/ob mouse phenotype.
|Figure 1. Hypothetical role of Leptin in the reproductive system. POMC = Proopiomelanocortin, a-MSH = alpha-melanocyte-stimulating hormone, OB-R = Leptin Receptor, MC4-R = MC4 Receptor, LH = Luteinizing hormone, LHRH = LH-releasing hormone, NO = Nitric Oxide|