Functional comparison of two evolutionary conserved insect neurokinin-like receptors.
Tachykinins are multifunctional neuropeptides that have been identified in vertebrates as well as invertebrates. The C-terminal FXGXRa-motif constitutes the consensus active core region of invertebrate tachykinins. In Drosophila, two putative G protein-coupled tachykinin receptors have been cloned: DTKR and NKD. This study focuses on the functional characterization of DTKR, the Drosophila ortholog of the stable fly's tachykinin receptor (STKR). Tachykinins containing an alanine residue instead of the highly conserved glycine (FXAXRa) display partial agonism on STKR-mediated Ca(2+)-responses, but not on cAMP-responses. STKR therefore seems to differentiate between a number of tachykinins. Gly- and Ala-containing tachykinins are both encoded in the Drosophila tachykinin precursor, thus raising the question of whether DTKR can also distinguish between these two tachykinin types. DTKR was activated by all Drosophila tachykinins and inhibited by tachykinin antagonists. Ala-containing analogs did not produce the remarkable activation behavior previously observed with STKR, suggesting different mechanisms of discerning ligands and/or activating effector pathways for STKR and DTKR.
Poels
Jeroen
J
Laboratory for Developmental Physiology, Genomics and Proteomics, Catholic University Leuven, Naamsestraat 59, B-3000 Leuven, Belgium.
Verlinden
Heleen
H
Fichna
Jakub
J
Van Loy
Tom
T
Franssens
Vanessa
V
Studzian
Kazimierz
K
Janecka
Anna
A
Nachman
Ronald J
RJ
Vanden Broeck
Jozef
J
D000818:Animals; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004330:Drosophila / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D007313:Insecta / Q000235:genetics / Q000378:metabolism*; D008024:Ligands; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism; D017981:Receptors, Neurotransmitter / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D018039:Receptors, Tachykinin / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D013373:Substance P / Q000031:analogs & derivatives / Q000494:pharmacology; D015320:Tachykinins / Q000494:pharmacology
D029721:Drosophila Proteins; D008024:Ligands; D009479:Neuropeptides; D017981:Receptors, Neurotransmitter; D018039:Receptors, Tachykinin; D015320:Tachykinins; C071259:TkR99D protein, Drosophila; C408989:spantide III; C065446:spantide II; D013373:Substance P; C042867:spantide