Major urinary protein (IPR002971)

Short name: Maj_urinary

Overlapping homologous superfamilies

Family relationships

  • Lipocalin (IPR002345)
    • Major urinary protein (IPR002971)


Rodent urinary proteins (mouse major urinary proteins or MUPs and rat alpha-2u globulins) are the major protein components of rodent urine and transport pheromones [PMID: 1279439]. Rodent urine contains an unusually large amount of protein. The major site of MUP synthesis is the liver; the protein is secreted by the liver into serum, where it circulates at relatively low levels before being rapidly filtered by the kidney and excreted. The sex-dependent expression of MUP (adult male mice secrete 5-20 times as much MUP as do females) and its ability to bind a number of odorant molecules is consistent with the suggestion that MUP acts as a pheromone transporter; the protein may be excreted into the urine carrying a bound pheromone, which is released as the urine dries and the protein denatures. The crystal structure of MUP has been solved [PMID: 1279439] and is known to be a member of the lipocalin family. Alpha-2u-globulin, a close homologue of MUP, accounts for 30-50% of total excreted protein in adult male rat urine. As its electrophoretic mobility is similar to that of serum a2 globulin, it was named 'alpha-2u-globulin', the subscript 'u' denoting its origin in urine. Alpha-2u-globulin is secreted into the plasma by a number of tissues, where it circulates before filtration through the kidney; between 20 and 50% is reabsorbed by the proximal tubule of the nephron, the rest being excreted. Although the exact physiological role of alpha-2u-globulin is unclear, there is circumstantial evidence that it functions in pheromone transport. This is consistent with its observed binding properties, its close similarity with MUP and the known properties of male rat urine.

Some of the proteins in this family are allergens. Allergies are hypersensitivity reactions of the immune system to specific substances called allergens (such as pollen, stings, drugs, or food) that, in most people, result in no symptoms. A nomenclature system has been established for antigens (allergens) that cause IgE-mediated atopic allergies in humans [WHO/IUIS Allergen Nomenclature Subcommittee King T.P., Hoffmann D., Loewenstein H., Marsh D.G., Platts-Mills T.A.E., Thomas W. Bull. World Health Organ. 72:797-806(1994)]. This nomenclature system is defined by a designation that is composed of the first three letters of the genus; a space; the first letter of the species name; a space and an arabic number. In the event that two species names have identical designations, they are discriminated from one another by adding one or more letters (as necessary) to each species designation.

The allergens in this family include allergens with the following designations: Mus m 1 and Rat m 1.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.