5-Hydroxytryptamine1A receptor synthetic peptides. Mechanisms of adenylyl cyclase inhibition.
The 5-hydroxytryptamine1A receptor (5-HT1AR) is a G-protein-coupled receptor negatively coupled to adenylyl cyclase (AC). We have studied the functional domains of 5-HT1AR using synthetic peptides to block or mimic receptor function. The entire second intracellular loop (5-HT1AR-i2) and the carboxyl end of the third intracellular loop (5-HT1AR-i3-C) strongly inhibited forskolin-stimulated AC activity. These effects were not additive with those of 5-HT. Like 5-HT, the peptides 5-HT1AR-i3-C and -i2 weakly inhibited AIF4- and Mn2+ stimulated AC activity. 5-HT1AR binding assays indicated that peptides could interact with the same G-protein pool as the 5-HT1AR. 5-HT1AR-i3-C- and -i2-stimulated [35S]guanosine 5'-O-(thiotriphosphate) binding on Go/Gi proteins. Only 5-HT1AR-i3-C partially adopted an alpha-helical conformation in solution. These data show that different domains in the 5-HT1AR second and third intracellular loops can couple to and activate Gi proteins in order to mediate AC inhibition. Peptide-induced AC inhibition was not sensitive to pertussis toxin as opposed to the 5-HT1AR-mediated effect. Our data show that the 5-HT1AR and the 5-HT1AR peptides activate Gi proteins in a slightly different manner.
Varrault
A
A
CNRS UPR 9023, Montpellier, France.
Le Nguyen
D
D
McClue
S
S
Harris
B
B
Jouin
P
P
Bockaert
J
J
D016475:3T3 Cells; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000378:metabolism; D037361:Adenylate Cyclase Toxin; D000067956:Adenylyl Cyclase Inhibitors; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D002999:Clone Cells; D005576:Colforsin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D019204:GTP-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006624:Hippocampus / Q000201:enzymology; D006801:Humans; D007700:Kinetics; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009036:Moths; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000494:pharmacology*; D037342:Pertussis Toxin; D017433:Protein Structure, Secondary; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000737:chemistry* / Q000378:metabolism*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D037361:Adenylate Cyclase Toxin; D000067956:Adenylyl Cyclase Inhibitors; D010446:Peptide Fragments; D011985:Receptors, Serotonin; D010566:Virulence Factors, Bordetella; D005576:Colforsin; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D006160:Guanosine Triphosphate; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins