Year-end Sale % OFF 
Abstract
The existence of dopamine D1C and D1D receptors in Xenopus and chicken, respectively, challenged the established duality (D1A and D1B) of the dopamine D1 receptor class in vertebrates. To ascertain the molecular diversity of this gene family in early diverging vertebrates, we isolated four receptor-encoding sequences from the European eel Anguilla anguilla. Molecular phylogeny assigned two receptor sequences (D1A1 and D1A2) to the D1A subtype, and a third receptor to the D1B subtype. Additional sequence was orthologous to the Xenopus D1C receptor and to several other previously unclassified fish D1-like receptors. When expressed in COS-7 cells, eel D1A and D1B receptors display affinity profiles for dopaminergic ligands similar to those of other known vertebrate homologues. The D1C receptor exhibits pharmacological characteristics virtually identical to its Xenopus homologue. Functionally, while all eel D1 receptors stimulate adenylate cyclase, the eel D1B receptor exhibits greater constitutive activity than either D1A or D1C receptors. Semiquantitative reverse transcription-polymerase chain reaction reveals the differential distribution of D1A1, D1A2, D1B, and D1C receptor mRNA within the hypothalamic-pituitary axis of the eel brain. Taken together, these data suggest that the D1A, D1B, and D1C receptors arose prior to the evolutionary divergence of fish and tetrapods and exhibit molecular, pharmacological, and functional attributes that unambiguously allow for their classification as distinct D1 receptor subtypes in the vertebrate phylum.
Highlights
The existence of dopamine D1C and D1D receptors in Xenopus and chicken, respectively, challenged the established duality (D1A and D1B) of the dopamine D1 receptor class in vertebrates
We report here that (a) eel dopamine D1 receptors are comprised of three distinct D1 receptor subtypes, which express molecular, pharmacological, and functional signatures that define unequivocally the characteristics of vertebrate D1A, D1B, and D1C receptors; (b) the diversity of the vertebrate D1 receptor gene family occurred and was clearly established before the divergence of actinopterygians from sarcopterygians
Since none of the receptors displayed guanine nucleotide sensitivity, consistent with previous observations [6, 7], it is possible to directly compare affinities of these receptors with their vertebrate/mammalian counterparts expressed in the same cells and Estimated dissociation constant (Ki) values of various dopaminergic compounds for the inhibition of [3H]SCH-23390 binding to A. anguilla dopamine D1A1, D1A2, D1B, and D1C receptors expressed in COS-7 cells are listed in order of their potency for the D1A2 receptor subtype
Summary
The existence of dopamine D1C and D1D receptors in Xenopus and chicken, respectively, challenged the established duality (D1A and D1B) of the dopamine D1 receptor class in vertebrates. Cloning and Sequencing of Four Distinct D1-like Receptor Sequences in the European Eel—Amplification of eel genomic DNA by PCR with D1 specific primers generated a fragment that upon sequence analysis displayed 74% identity with transmembrane segments III–VII of the rat D1A receptor gene.
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
