Major urinary proteins, alpha(2U)-globulins and aphrodisin

Area of Science:

• Biochemistry
• Animal Behavior
• Genetics

Background:

• Major urinary proteins (MUPs) are secreted by the liver and kidneys in male rodents, also known as alpha(2U)-globulins in rats.
• The MUP family includes related proteins excreted by exocrine glands, forming a multi-gene family with complex hormonal and tissue-specific regulation.
• MUP gene expression exhibits significant polymorphism across species, strains, sexes, and individuals, with evidence of both evolutionary conservation and divergence.

Purpose of the Study:

• To investigate the structure, function, and evolutionary aspects of major urinary proteins (MUPs) in rodents.
• To understand the role of MUPs in olfactory signaling and their interaction with odorant molecules.
• To compare MUPs with other lipocalins, such as aphrodisin, in the context of chemosensory communication.

Main Methods:

• Analysis of MUP gene family structure and expression regulation.
• Structural comparison of MUPs with other lipocalins.
• Investigation of MUPs' binding affinity for small natural odorant molecules.
• Assessment of MUPs' role in olfactory signaling and reproductive behaviors.

Main Results:

• MUPs share a conserved beta-barrel structure with a hydrophobic pocket, similar to other lipocalins.
• MUPs bind small odorant molecules with medium affinity and release them slowly, creating lasting olfactory traces.
• MUPs are involved in chemosensory signaling and may prime endocrine reactions in female rodents.
• Aphrodisin, a hamster lipocalin, stimulates male behavior but does not appear to bind odorants and lacks polymorphism.

Conclusions:

• MUPs function as crucial odorant carriers in rodents, contributing to complex olfactory communication.
• The structural and functional characteristics of MUPs highlight their importance in intraspecific signaling.
• Comparative analysis with aphrodisin reveals distinct roles for lipocalins in rodent sensory systems.