Characterization of a common VIP-PACAP receptor in human small intestinal epithelium.
Vasoactive intestinal peptide (VIP) receptors were characterized in epithelial plasma membranes from human small intestine. Native VIP inhibited the binding of 125I-labeled VIP to jejunal membranes, and Scatchard analysis of these data was consistent with the existence of one class of receptor with a dissociation constant of 42 pM and a maximal binding of 256 fmol/mg membrane protein. VIP stimulated adenylyl cyclase activity in human jejunal membranes in the 0.01 nM-1 microM range [half-maximal effective dose = 0.7 nM]. Coupling of VIP receptors with a Gs protein was further assessed by the ability of GTP (10(-8) to 10(-3) M) to inhibit 125I-VIP binding to membranes. 125I-VIP binding was seven to eight times higher in villus cells than in crypt cells. Finally, 125I-VIP binding was detectable throughout the small and large intestines with the highest binding in jejunum. Among the natural peptides structurally related to VIP, some inhibited 125I-VIP binding with the following order of potency: VIP = pituitary adenylate cyclase-activating peptide (PACAP)-27 = PACAP-38 > helodermin >> peptide histidine methionineamide = human growth hormone-releasing factor > secretin. The same order of potency of peptides for inhibiting 125I-VIP or 125I-labeled PACAP was observed, supporting that the two tracers bound to a common VIP-PACAP receptor site. This order of potency was also observed for the stimulation of adenylyl cyclase activity by these peptides. 125I-VIP was cross-linked to membranes using disuccinimidyl suberate. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, one single band of 70,000 mol wt was observed.(ABSTRACT TRUNCATED AT 250 WORDS)
Institut National de la Santé et de la Recherche Médicale, Unité 239, Faculté de Médecine X. Bichat, Paris, France.
R
R
Salomon
A
A
Couvineau
C
C
Rouyer-Fessard
T
T
Voisin
D
D
Lavallée
A
A
Blais
D
D
Darmoul
M
M
Laburthe
D001667:Binding, Competitive; D016922:Cellular Senescence; D004591:Electrophoresis, Polyacrylamide Gel; D004848:Epithelium; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D007583:Jejunum / Q000166:cytology / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011964:Receptors, Gastrointestinal Hormone / Q000378:metabolism*; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D011979:Receptors, Pituitary Hormone; D018005:Receptors, Vasoactive Intestinal Peptide; D014018:Tissue Distribution; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism
C495401:ADCYAP1 protein, human; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011956:Receptors, Cell Surface; D011964:Receptors, Gastrointestinal Hormone; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D011979:Receptors, Pituitary Hormone; D018005:Receptors, Vasoactive Intestinal Peptide; D014660:Vasoactive Intestinal Peptide