The novel VIP-like hypothalamic polypeptide PACAP interacts with high affinity receptors in the human neuroblastoma cell line NB-OK.
We investigated the ability of two forms of Pituitary Adenylate Cyclase Activating Polypeptide [PACAP-38, the 38 amino acid peptide isolated from ovine hypothalamus, and PACAP-27, a shorter N-terminal (1-27) amidated version] to interact with specific receptors in membranes from the human neuroblastoma cell line NB-OK. [125I]PACAP-27 bound rapidly and specifically to one class of high affinity sites (Kd 0.5 nM). VIP inhibited [125I]PACAP-27 binding 300- to 1000-fold less potently than PACAP-27 and PACAP-38. One microM PHI prevented tracer binding only partially and secretin, glucagon and GRF(1-29)NH2 were ineffective in this respect. PACAP-27 and PACAP-38 stimulated adenylate cyclase activity dose dependently and with similar efficacy (Kact 0.2-0.3 nM), this activation being compatible with the occupancy of specific high affinity PACAP receptor. VIP was markedly less potent and less efficient on this enzyme than PACAP. Chemical cross-linking of [125I]PACAP-27 followed by SDS-PAGE and autoradiography revealed specific cross-linking with a 68 kDa protein.
Cauvin
A
A
Department of Biochemistry and Nutrition, Medical School, Université Libre de Bruxelles, Belgium.
Buscail
L
L
Gourlet
P
P
De Neef
P
P
Gossen
D
D
Arimura
A
A
Miyata
A
A
Coy
D H
DH
Robberecht
P
P
Christophe
J
J
D000262:Adenylyl Cyclases / Q000378:metabolism; D000595:Amino Acid Sequence; D006801:Humans; D007028:Hypothalamic Hormones / Q000138:chemical synthesis / Q000378:metabolism*; D007457:Iodine Radioisotopes; D008969:Molecular Sequence Data; D009447:Neuroblastoma / Q000378:metabolism*; D009479:Neuropeptides / Q000138:chemical synthesis / Q000378:metabolism*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011956:Receptors, Cell Surface / Q000378:metabolism*; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D011979:Receptors, Pituitary Hormone; D012689:Sequence Homology, Nucleic Acid; D014407:Tumor Cells, Cultured
C495401:ADCYAP1 protein, human; D007028:Hypothalamic Hormones; D007457:Iodine Radioisotopes; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011956:Receptors, Cell Surface; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D011979:Receptors, Pituitary Hormone; D000262:Adenylyl Cyclases