Major urinary proteins (Mups) are a subfamily of proteins found in high abundance in the urine and other secretions of many mammals. They belong to a larger family of proteins known as lipocalins. Mups are encoded by a cluster of genes located on a single stretch of DNA, varying greatly in number between species: from at least 21 functional genes in mice to none in humans. Mups form a characteristic glove shape, encompassing a ligand-binding pocket that accommodates specific small, organic chemicals. Urinary proteins were first reported in rodents in 1932, during studies by Thomas Addis into the cause of proteinuria. They are potent human allergens largely responsible for a number of animal allergies. Their endogenous function within an animal is unknown, but as secreted proteins, they can act as pheromones or function as pheromone transporters and stabilizers, playing multiple roles in chemical communication between animals. They have been demonstrated to promote aggression in male mice, and one specific Mup found in male mouse urine is sexually attractive to female mice. Mups can also function as signals between different species. Accordingly, Mups can provide a range of identifying information about the donor animal. (more...)
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