Abstract
We have compared the binding of [125I]vasoactive intestinal polypeptide (VIP) to human brain membranes with that of [125I]PACAP27. [125I]VIP was displaced by PACAP27, VIP and two synthetic peptides, peptide-1 (N-terminal PACAP27/C-terminal VIP) and peptide-2 (N-terminal VIP/C-terminal PACAP27), but the IC50 of PACAP27 and peptide-1 were 10-20 times lower than those of VIP and peptide-2. [125I]PACAP27 was readily displaced by PACAP27 and peptide-1, with an IC50 of less than 1 nM, but poorly by VIP and peptide-2. Chemical cross-linking revealed that both labels were bound to polypeptides of Mr 66,000 and Mr 50,000. The results indicate that in human brain membranes both binding sites have a higher affinity to the N-terminal sequence of PACAP27, and VIP binding sites prefer PACAP27 to VIP itself.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adenylyl Cyclases / metabolism
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Amino Acid Sequence
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Humans
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Molecular Sequence Data
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Neuropeptides / metabolism*
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Peptide Fragments / metabolism
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Pituitary Adenylate Cyclase-Activating Polypeptide
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Receptors, Cell Surface / metabolism*
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Receptors, Gastrointestinal Hormone / metabolism*
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Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide
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Receptors, Pituitary Hormone*
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Receptors, Vasoactive Intestinal Peptide
Substances
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ADCYAP1 protein, human
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Neuropeptides
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Peptide Fragments
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Pituitary Adenylate Cyclase-Activating Polypeptide
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Receptors, Cell Surface
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Receptors, Gastrointestinal Hormone
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Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide
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Receptors, Pituitary Hormone
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Receptors, Vasoactive Intestinal Peptide
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Adenylyl Cyclases