The activation of adenylate cyclase by pituitary adenylate cyclase activating polypeptide (PACAP) via helodermin-preferring VIP receptors in human SUP-T1 lymphoblastic membranes.
Competition binding curves, using [125I-acetyl-His1]PACAP-27 as radioligand and dose-effect curves of adenylate cyclase activation in human SUP-T1 lymphoblastic membranes showed that PACAP-27 and PACAP-38 stimulate the enzyme through a single class of helodermin-preferring VIP receptors with the following order of potency: helodermin = [acetyl-His1]PACAP-27 greater than PACAP-38 greater than PACAP-27 greater than VIP. PACAP (6-27) (Ki 0.5-0.8 microM) and [Des-His1, Asn3]PACAP-27 (Ki 1-2 microM) acted as competitive antagonists. Using a series of 13 PACAP-27 analogues and fragments and three VIP analogues, we identified positions 1, 2, 3, 9 and 13 in PACAP-27 as being of importance for high-affinity binding. Thus, we added further evidence for considering that the present helodermin-preferring VIP receptors, when compared to a majority of VIP receptors and PACAP receptors, exhibit an original specificity pattern.
Gourlet
P
P
Department of Biochemistry and Nutrition, Medical School, Université Libre de Bruxelles, Belgium.
De Neef
P
P
Woussen-Colle
M C
MC
Vandermeers
A
A
Vandermeers-Piret
M C
MC
Robberecht
P
P
Christophe
J
J
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000595:Amino Acid Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D007700:Kinetics; D008214:Lymphocytes / Q000378:metabolism*; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011869:Radioligand Assay; D011964:Receptors, Gastrointestinal Hormone / Q000378:metabolism*; D018005:Receptors, Vasoactive Intestinal Peptide; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism
C495401:ADCYAP1 protein, human; D036341:Intercellular Signaling Peptides and Proteins; D009479:Neuropeptides; D010455:Peptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011964:Receptors, Gastrointestinal Hormone; D018005:Receptors, Vasoactive Intestinal Peptide; D014660:Vasoactive Intestinal Peptide; C040442:heliodermin; D000262:Adenylyl Cyclases