The novel VIP-like hypothalamic polypeptide PACAP interacts with high affinity receptors in the human neuroblastoma cell line NB-OK.
Cauvin. A A; 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
Key Findings
- PACAP‑27 and PACAP‑38 bind to high‑affinity sites (Kd ~0.5 nM) on NB‑OK cells.
- VIP can block PACAP binding but is 300‑ to 1000‑fold less potent.
- GRF‑1‑29 (GHRH) does not affect PACAP binding, indicating it uses different receptors.
- PACAP activation of adenylate cyclase occurs at low nanomolar concentrations, confirming functional receptors.
- A 68 kDa protein was identified as the likely PACAP receptor via cross‑linking.
Practical Outcomes
- For biohackers, this paper mainly confirms that GRF‑1‑29 does not act through PACAP receptors, so it won’t influence the same signaling pathways. The findings don’t suggest new dosing strategies or direct health benefits, but they reinforce that PACAP and GRF work via distinct mechanisms.
Summary
The study shows that the brain peptide PACAP binds strongly to specific receptors on human neuroblastoma cells, while similar peptides like VIP are much weaker and the growth hormone‑releasing peptide GRF‑1‑29 does not bind these receptors at all.
Abstract
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.
Study Information
pubmed
1990
10.1016/0196-9781(90)90194-a