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Molecular cloning of putative odorant-binding and odorant-metabolizing proteins
T N Dear1, K Campbell, T H Rabbitts
1MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.
Abstract:
Olfactory reception occurs via the interaction of odorants with the chemosensory cilia of the olfactory receptor cells located in the nasal epithelium. The cDNA clones from mRNA specific to olfactory mucosa were studied. One of these clones, OBPII, encodes a secretory protein with significant homology to odorant-binding protein (OBP), a protein with broad odorant-binding ability, and is expressed in the lateral nasal gland, which is the site of expression of OBP. The OBPII sequence also shows significant homology to the VEG protein, which is thought to be involved in taste transduction. OBPII is a new member of the lipophilic molecule carrier protein family. The second cDNA clone encodes a novel homologue of glutathione peroxidase, an enzyme involved in cellular biotransformation pathways. Its expression appears to be localized to the Bowman's glands, the site of several previously identified olfactory-specific biotransformation enzymes.
Insights
Researchers identified two novel olfactory molecules. One, OBPII, is a lipophilic molecule carrier similar to odorant-binding protein (OBP). The second is a glutathione peroxidase homologue found in Bowman's glands.
Area of Science:
- Olfactory Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Olfactory reception involves odorant interaction with olfactory receptor cells in the nasal epithelium.
- Specific mRNA from olfactory mucosa was analyzed to identify novel olfactory-specific proteins.
- Odorant-binding proteins (OBPs) are known for broad odorant-binding abilities.
Purpose of the Study:
- To identify and characterize novel cDNA clones from olfactory mucosa.
- To investigate the function and localization of newly discovered olfactory proteins.
- To explore the role of these proteins in olfactory reception and biotransformation pathways.
Main Methods:
- cDNA library construction from olfactory mucosa mRNA.
- Sequence analysis and homology searches for identified clones.
- Expression localization studies within the nasal epithelium.
Main Results:
- One cDNA clone, OBPII, encodes a secretory protein homologous to OBP and VEG proteins, identified as a lipophilic molecule carrier protein.
- OBPII is expressed in the lateral nasal gland, a known site for OBP expression.
- A second cDNA clone encodes a novel glutathione peroxidase homologue, expressed in Bowman's glands, suggesting a role in biotransformation.
Conclusions:
- OBPII represents a new member of the lipophilic molecule carrier protein family involved in olfactory processes.
- The novel glutathione peroxidase homologue is localized to Bowman's glands, implicating it in olfactory-specific biotransformation.
- These findings expand the understanding of molecular mechanisms underlying smell reception and processing.