Presence of highly selective receptors for PACAP (pituitary adenylate cyclase activating peptide) in membranes from the rat pancreatic acinar cell line AR 4-2J |
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Authors: | L Buscail P Gourlet A Cauvin P De Neef D Gossen A Arimura A Miyata D H Coy P Robberecht J Christophe |
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Institution: | Department of Biochemistry and Nutrition, Medical School, Université Libre de Bruxelles, Belgium. |
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Abstract: | We characterized highly selective receptors for PACAP, the pituitary adenylate cyclase activating peptide, in the tumoral acinar cell line AR 4-2J derived from the rat pancreas. PACAP, a novel hypothalamic peptide related to vasoactive intestinal peptide (VIP), was tested as the full natural 38-residue peptide (PACAP-38) and as an N-terminal amidated 27-residue derivative (PACAP-27). The binding sites showed considerable affinity for 125I]PACAP-27 (Kd = 0.4 nM) and PACAP-38, while their affinity for VIP and the parent peptide helodermin was 1000-fold lower. These receptors were coupled to adenylate cyclase, the potency of PACAP-38 and PACAP-27 (Kact = 0.2 nM) being much higher than that of VIP (Kact = 100 nM) and helodermin (Kact = 30 nM). Chemical cross-linking of 125I]PACAP-27 followed by SDS-PAGE and autoradiography revealed a specifically cross-linked peptide with an Mr of 68,000 (including 3000 for one PACAP-27 molecule). |
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