Characterization of [125I]Tyr11-somatostatin binding sites in the rabbit retina.
We have identified specific receptors for somatostatin (SS) in the rabbit retina using the radioligand [125I]Tyr11-Somatostatin. [125I]Tyr11-SS bound with high affinity to retinal membranes as was ascertained by both kinetic and saturation experiments. Scatchard analysis of the saturation data for [125I]Tyr11-SS binding to retinal membranes suggest a single population of sites with an apparent affinity constant (KD) of 0.90 +/- 0.20 nM and a maximum number of binding sites (Bmax) of 104 +/- 52 fmol/mg protein. The specific binding of [125I]Tyr11-SS was displaced in a dose-dependent manner by SS, Tyr11-SS, SMS 201-995, SS-28 and D-Trp8-SS. The inactive SS analog SS28(1-14) as well as the peptides CRF and bombesin had no effect. In addition, the specific binding of [125I]Tyr11-SS was attenuated by GTPgS. These findings demonstrate the presence of a selective receptor for SS in the rabbit retina that is coupled to guanine nucleotide binding protein(s).
Department of Basic Sciences, School of Health Sciences, University of Crete, Heraklion, Greece.
G
G
Liapakis
K
K
Thermos
D000818:Animals; D001665:Binding Sites; D007457:Iodine Radioisotopes; D008297:Male; D011817:Rabbits; D017981:Receptors, Neurotransmitter / Q000032:analysis*; D017481:Receptors, Somatostatin; D012160:Retina / Q000737:chemistry*; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000378:metabolism
D007457:Iodine Radioisotopes; D017981:Receptors, Neurotransmitter; D017481:Receptors, Somatostatin; D013004:Somatostatin; C032367:somatostatin, Tyr(11)-