title: Binding of monoiodinated neuropeptide Y to hippocampal membranes and human neuroblastoma cell lines.
abstract: Monoiodinated radioligands of the homologous 36-amino acid peptides, neuropeptide Y (NPY) and peptide YY, were prepared by reverse phase high performance liquid chromatography with isocratic elution. [125I-Tyr1]- and [125I-Tyr36]monoiodoNPY bound equally well to a single class of high affinity binding sites on synaptosomal membranes prepared from porcine hippocampus (Kd = 1.0 X 10(-10) M) whereas iodine substitution in Tyr27, for example, partly interfered with the receptor binding. The receptors on the hippocampal membranes did not distinguish between neuropeptide Y and peptide YY either in their monoiodinated or in their unlabeled forms. Six out of twelve human neuroblastoma cell lines had high affinity binding sites for monoiodinated NPY ranging from 2 to 145 X 10(3) sites per cell. The NPY binding to three of the cell lines, SMS-MSN, SMS-KAN, and CHP-234 was of relatively high affinity (Kd = 1.3 to 6.1 X 10(-10) M), and, as in the hippocampal membranes, the long C-terminal fragment, NPY(13-36)peptide was also a relatively potent ligand for these receptors. Two other neuroblastoma cell lines, MC-IXC and CHP-212, expressed NPY receptors characterized by a lower affinity (Kd = 4.8 and 24.6 X 10(-9) M) and negligible cross-reactivity with the C-terminal fragment. It is concluded that monoiodinated radioligands of the tyrosine-rich neuropeptide Y can be prepared and that receptors for these ligands in two apparently different subtypes are found on a series of human neuroblastoma cell lines.
authors.affiliation: Laboratory of Molecular Endocrinology, University Department of Clinical Chemistry, Rigshospitalet, Copenhagen, Denmark.
authors.forename: S P
authors.initials: SP
authors.lastname: Sheikh
authors.forename: M M
authors.initials: MM
authors.lastname: O'Hare
authors.forename: O
authors.initials: O
authors.lastname: Tortora
authors.forename: T W
authors.initials: TW
authors.lastname: Schwartz
mesh_terms: D000818:Animals; D001665:Binding Sites; D006624:Hippocampus / Q000378:metabolism*; D006801:Humans; D007467:Iodoproteins / Q000378:metabolism; D007700:Kinetics; D009447:Neuroblastoma / Q000378:metabolism*; D009478:Neuropeptide Y / Q000378:metabolism*; D019894:Peptide YY; D010455:Peptides / Q000378:metabolism; D013552:Swine; D014407:Tumor Cells, Cultured; D014443:Tyrosine
chemical_list: D007467:Iodoproteins; D009478:Neuropeptide Y; D010455:Peptides; D019894:Peptide YY; D014443:Tyrosine