Abstract
Many biological processes involve globular transport proteins belonging to a family called lipocalins. Among wide spectrum of lipocalins, Major Urinary Proteins (Mup) and Odorant Binding Proteins (Obp) are well known for their capacity to bind and carry odorants / pheromones and have been studied to detail in various mammalian models.
However, many lipocalins have previously been described with respect to their protective function in mammalian organism where they transport potentially harmful molecules to a degradation site or straight out of the body. In addition to a role of lipocalins in chemical communication this review presents lipocalins from the point of view of the "toxic waste hypothesis".
This hypothesis assumes that members of lipocalins that are linked to a metabolic degradation of their ligands were an ideal source for natural selection during evolution due to an ability of potential receivers to detect lipocalin ligands levels as a signal by other individuals.