Radioreceptor assay for detergent-solubilized rat insulinoma growth hormone receptors.

Growth hormone receptors from a rat insulinoma cell line, RIN-5AH were solubilized in the non-ionic detergent Triton X-100. A radioreceptor assay based on polyethylene glycol precipitation of the growth hormone: receptor complex showed time-dependent and saturable hormone binding. The affinity in detergent solution for biosynthetic human growth hormone of approx. 6 ng/ml was found similar to that of intact RIN cells. The solubilization and receptor assay conditions described are useful for further characterization and purification of RIN cell growth hormone receptors, which might provide an initial insight into the molecular mechanism of the growth hormone effects on islet beta-cells.