Structural requirements for the binding of the pituitary adenylate-cyclase-activating peptide to receptors and adenylate-cyclase activation in pancreatic and neuronal membranes.
PACAP (pituitary adenylate-cyclase-activating peptide)-binding receptors were investigated in membranes from the rat pancreatic acinar cell line, AR 4-2J, the rat hippocampus and the human neuroblastoma cell line NB-OK, by 125I-PACAP(1-27) (amino acid residues 1-27 of N-terminal amidated PACAP) binding and adenylate cyclase activation. The relative binding of 125I-PACAP(1-27) to the receptor, and ability to activate adenylate cyclase were PACAP greater than or equal to PACAP(1-27) greater than PACAP(2-38) greater than PACAP(1-9)-VIP(10-28)(PACAP-VIP) greater than PACAP(2-27) greater than [Ser9,Tyr13]VIP greater than [Tyr13]VIP greater than or equal to [Ser9]VIP greater than or equal to VIP(1-23)-PACAP(24-27)(VIP-PACAP) greater than VIP (vasoactive intestinal peptide). The N-terminal moiety of PACAP(1-27) was more important than the three amino acids at the C-terminus for 125I-PACAP(1-27)-binding site recognition. For rat pancreatic 125I-VIP-binding sites tested with 125I-VIP, the order of binding affinity was PACAP = PACAP(1-27) greater than or equal to VIP = [Ser9]VIP = [Tyr13]VIP = [Ser9,Try13]VIP greater than or equal to PACAP-VIP greater than or equal to VIP-PACAP greater than PACAP(2-38) = PACAP(2-27). Pancreatic 125I-VIP-binding sites, when compared to 125I-PACAP(1-27)-binding sites, showed little specificity and only weak coupling, so that PACAP and VIP-PACAP acted only as partial VIP agonists on adenylate cyclase.
Gourlet
P
P
Department of Biochemistry and Nutrition, Medical School, Université Libre de Bruxelles, Belgium.
Woussen-Colle
M C
MC
Robberecht
P
P
de Neef
P
P
Cauvin
A
A
Vandermeers-Piret
M C
MC
Vandermeers
A
A
Christophe
J
J
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002462:Cell Membrane / Q000201:enzymology; D002678:Chimera; D004789:Enzyme Activation; D006624:Hippocampus / Q000201:enzymology*; D006801:Humans; D008969:Molecular Sequence Data; D009447:Neuroblastoma / Q000201:enzymology*; D009474:Neurons / Q000201:enzymology; D009479:Neuropeptides / Q000737:chemistry*; D010190:Pancreatic Neoplasms / Q000188:drug therapy / Q000201:enzymology*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051381:Rats; D014407:Tumor Cells, Cultured; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism
C495401:ADCYAP1 protein, human; C495403:Adcyap1 protein, rat; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D014660:Vasoactive Intestinal Peptide; D000262:Adenylyl Cyclases