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Odorant signal termination by olfactory UDP glucuronosyl transferase
1Department of Membrane Research, Weizmann Institute of Science, Rehovot, Israel.
Nature
|February 28, 1991
Summary
Olfactory signal termination relies on more than just cytochrome P450 enzymes. Researchers identified an olfactory-specific UDP glucuronosyl transferase (UGT) that modifies odorants, effectively ending olfactory signals.
Area of Science:
- Biochemistry
- Neuroscience
- Molecular Biology
Background:
- Olfactory transduction (how smells are detected) is well-studied, but how olfactory signals end is less understood.
- Cytochrome P450 monooxygenases are suspected termination enzymes, but their reactions may not sufficiently alter odorant properties.
- Phase II biotransformation enzymes, like UDP glucuronosyl transferase (UGT), are crucial for drug detoxification in other tissues by altering solubility.
Purpose of the Study:
- To investigate the role of UDP glucuronosyl transferase (UGT) in olfactory signal termination.
- To clone and characterize an olfactory-specific UGT and assess its substrate specificity and function.
Main Methods:
- Molecular cloning and expression of an olfactory-specific UGT.
- Enzymatic assays comparing olfactory UGT with liver UGT activity on odorants and standard substrates.
- Assessing the effect of glucuronic acid conjugation on odorant-stimulated adenylyl cyclase activity.
Main Results:
- An olfactory-specific UGT was successfully cloned and expressed.
- The olfactory UGT demonstrated a preference for odorants over typical UGT substrates.
- Glucuronidation by the olfactory UGT inactivated odorants' ability to stimulate olfactory adenylyl cyclase.
Conclusions:
- Olfactory UGT plays a significant role in terminating diverse olfactory signals.
- This enzyme contributes to olfactory signal termination by altering odorant properties and reducing their signaling capacity.
- The findings suggest a broader enzymatic mechanism for olfactory signal termination than previously thought.