Ligand association with the rabbit kidney and brain Y₁, Y₂ and Y₅-like neuropeptide Y (NPY) receptors shows large subtype-related differences in sensitivity to chaotro

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• 作者：Parker ; Steven L. ; Parker ; Michael S.
• 关键词：Receptor subtype ; Hydrophobic pocket ; Alkylator sensitivity ; NPY ; neuropeptide Y ; PYY ; peptide YY ; LP-PYY ; (Leu³¹ ; Pro³⁴) human peptide YY ; PYY(3&ndash ; 36) ; human peptide YY(3&ndash ; 36) ; hPP ; human pancreatic polypeptide ; rPP ; rat pan
• 刊名：Regulatory Peptides
• 出版年：2000
• 出版时间：February 8, 2000
• 年：2000
• 卷：87
• 期：1-3
• 页码：59-72
• 全文大小：848 K

文摘

The binding to rabbit kidney or hypothalamic particulates of the subtype-selective neuropeptide Y (NPY) receptor ligands [¹²⁵I](Leu³¹,Pro³⁴)hPYY (as Y₁ site label at 2 nM human pancreatic polypeptide (hPP)), [¹²⁵I]-hPYY(3–36) (Y₂ label), and [¹²⁵I]-hPP (Y₅ label) displayed great differences in sensitivity to alkylators and chaotropic agents. Sensitivity to a nonionic chaotrope, urea, was much higher for the Y₁ binding than for the Y₅-like binding or the Y₂ binding. The non-selective alkylator N-ethylmaleimide (NEM) and several alkylators selective for aminergic receptors were much more efficacious against the Y₁ relative to the Y₂ binding. Similar differences could be confirmed with the attachment of Y₁ and Y₂-selective tracers to CHO cells expressing the cloned guinea-pig Y₁ or Y₂ receptors. The Y₅-like binding was quite insensitive to NEM, but sensitive to chloroethylclonidine (CEC) and prazobind, which were less potent at the Y₁, and especially at the Y₂ site. The unrestricted-access alkylator 2-aminoethyl methanethiosulfonate inhibited the binding to all subtypes, while the restricted-access agent 2-(trimethylammonium)ethylmethanethiosulfonate poorly inhibited the Y₅-like binding, or the guanine nucleotide-insensitive Y₂ binding. These results are compatible with an active conformation of the Y₅-like site dependent on maintenance of a shared hydrophobic cavity. The Y₂ sites resistant to guanosine polyphosphates and restricted-access alkylators were detected mainly in particulates slowly solubilized by cholate at 0–5°C; these sites could be clustered.