Demonstration of a specific [3H]INS(1,4,5)P3 binding site in rat heart sarcoplasmic reticulum.
Previous studies have suggested that inositol(1,4,5)-trisphosphate (InsP3) might induce release of Ca2+ by sarcoplasmic reticulum (SR) vesicles isolated from heart muscle. In this study binding sites specific for InsP3 in isolated SR vesicles from heart muscle were demonstrated. Scatchard analysis of a binding isotherm indicated two binding sites, viz a high affinity site with a Kd = 20 nM and Bmax = 4.2 pmol/mg protein and a low affinity site with a Kd = 424 nM and Bmax = 31 pmol/mg protein. Specificity of binding was demonstrated by using structural analogues. In addition to the finding of binding sites for InsP3, this membrane preparation also demonstrated a possible binding site for InsP4.
Department of Medical Physiology and Biochemistry, University of Stellenbosch Medical School, Tygerberg, Republic of South Africa.
B
B
Huisamen
R
R
Mouton
L H
LH
Opie
A
A
Lochner
D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000032:analysis* / Q000378:metabolism; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008297:Male; D009124:Muscle Proteins / Q000032:analysis* / Q000378:metabolism; D009206:Myocardium / Q000737:chemistry*; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D018160:Receptors, Cytoplasmic and Nuclear / Q000032:analysis* / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000737:chemistry*; D015290:Second Messenger Systems
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D009124:Muscle Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium