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Cloning and expression of a fish alpha 2-adrenoceptor
S P Svensson1, T J Bailey, D J Pepperl
1Department of Pharmacology & Toxicology, College of Pharmacy, University of Arizona, Tucson 85721.
British Journal of Pharmacology
|September 1, 1993
Summary
Researchers cloned the alpha 2-F receptor from cuckoo wrasse skin, revealing its role in pigment aggregation. This fish alpha 2-adrenoceptor shares characteristics with human subtypes, potentially representing an ancestral form.
Area of Science:
- Pharmacology
- Molecular Biology
- Genetics
Background:
- Pigment aggregation in fish melanophores is mediated by alpha 2-adrenoceptors.
- The specific fish alpha 2-receptor subtype involved was previously uncharacterized.
Purpose of the Study:
- To clone and characterize a novel fish alpha 2-adrenoceptor from the cuckoo wrasse (Labrus ossifagus).
- To investigate the pharmacological properties and potential evolutionary significance of this fish receptor.
Main Methods:
- Polymerase chain reaction (PCR) using degenerate oligonucleotides based on human alpha 2-adrenoceptor subtypes.
- Screening of a cuckoo wrasse genomic library to obtain the full gene sequence.
- Expression of the cloned receptor in COS-7 cells and radioligand binding assays using [3H]-rauwolscine.
Main Results:
- Cloning of the alpha 2-F receptor gene, encoding a 432-amino acid protein with 47-57% identity to human alpha 2-adrenoceptors.
- Binding studies demonstrated high-affinity, saturable binding of [3H]-rauwolscine, with specific agonist and antagonist potency orders.
- Sequence analysis suggested potential regulation by cyclic AMP, calcium, and/or steroids.
Conclusions:
- The cloned alpha 2-F receptor exhibits pharmacological characteristics similar to human alpha2-C10 and alpha2-C4 subtypes.
- The alpha 2-F receptor may represent an ancestral alpha 2-adrenoceptor subtype, providing insights into receptor evolution.
- This fish receptor plays a role in pigment granule aggregation in melanophores.