D-[35S(U)]inositol 1,4,5-trisphosphorothioate, a novel radioligand for the inositol 1,4,5-trisphosphate receptor. Complex binding to rat cerebellar membranes.
D-[35S(U)]myo-inositol 1,4,5-trisphosphorothioate [( 35S]InsPS3), a synthetic, metabolically stable analogue of inositol 1,4,5-trisphosphate (InsP3), binds with high affinity (Kd 58.6 +/- 9.1 nM) to rat cerebellar membranes revealing a high density of specific binding sites (Bmax 21.5 +/- 2.1 pmol/mg of protein). Comparison with [3H]InsP3 binding reveals a higher density of sites labelled by [35S]InsPS3 and complex competition curves for displacement of specific [35S]InsPS3 by InsP3. The results suggest that [35S]InsPS3 labels two sites in rat cerebellar membranes with equal affinity: the InsP3 receptor and a site that displays low affinity for InsP3.
Challiss
R A
RA
Department of Pharmacology and Therapeutics, University of Leicester, UK.
Smith
S M
SM
Potter
B V
BV
Nahorski
S R
SR
D000818:Animals; D001667:Binding, Competitive; D015220:Calcium Channels; D002462:Cell Membrane / Q000378:metabolism; D002531:Cerebellum / Q000378:metabolism*; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism* / Q000031:analogs & derivatives; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007295:Inositol Phosphates / Q000378:metabolism* / Q000494:pharmacology; D007700:Kinetics; D008024:Ligands; D009946:Organothiophosphorus Compounds / Q000378:metabolism*; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear; D013462:Sulfur Radioisotopes
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007295:Inositol Phosphates; D008024:Ligands; D009946:Organothiophosphorus Compounds; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D013462:Sulfur Radioisotopes; C054737:inositol 1,4,5-triphosphorothioate; D015544:Inositol 1,4,5-Trisphosphate