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Human Y‐79 Retinoblastoma Cells Exhibit Specific Corticotropin‐Releasing Hormone Binding Sites
Author(s) -
Olianas Maria C.,
Lampis Giorgio,
Onali Pierluigi
Publication year - 1995
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1995.64010402.x
Subject(s) - corticotropin releasing hormone , radioligand , dissociation constant , binding site , medicine , receptor , endocrinology , guanosine , biology , peptide hormone , chemistry , biophysics , hormone , biochemistry
In this study we have identified specific binding sites for corticotropin‐releasing hormone (CRH) in human Y‐79 retinoblastoma cell membranes by using 125 I‐Tyrovine CRH ( 125 I‐oCRH) as radioligand. Binding at 19°C was rapid with steady state being reached within 20 min, reversible and linear with membrane protein concentration. The 125 I‐oCRH binding was enhanced by Mg 2+ and inhibited by the GTP analogue guanosine 5′‐ O ‐(3′‐thiotriphosphate). Y‐79 cell membranes exhibited two populations of binding sites, a high‐affinity site with an apparent dissociation constant ( K D ) of 1 n M and a low‐affinity site with an apparent K D of 500 n M . 125 I‐oCRH binding was completely antagonized by human/rat CRH, [Met(O) 21 ]oCRH, α‐helical CRH 9–41 , urotensin I, and sauvagine with a rank order of potency similar to that displayed by CRH receptors of other tissues. These data describe for the first time the presence of specific CRH‐binding sites in retinal cells. The Y‐79 cell line may therefore constitute a valuable model in which to study CRH action on retinal cells.