Solubilization of adenosine A1 binding sites from sheep cortex

³H]N⁶-cyclohexyladenosine binds with high affinity to sheep brain membranes with a drug specificity indicating an association with A₁ adenosine receptors. The ³H]N⁶-cyclohexyladenosine binding site has been solubilized with sodium cholate being the only detergent able to maintain specific binding after solubilization. After solubilization, the kinetics and drug specificity of binding are virtually identical with those obtained in the intact membranes, indicating a conservation of the binding site after removal of the receptor from its lipid environment. Gel filtration experiments indicated an apparent molecular weight of 400,000 for the receptor-detergent complex and a Stokes radius of 6.2 nm.