The influence of non-specific binding on scatchard analysis used in insulin/receptor binding studies with erythrocytes

Conclusions By equilibrium binding studies it could be demonstrated that erythrocytes have been saturated with specifically bound insulin in the order of 0.10–0.20 nmol/l with 4×10¹² erythrocytes/l. From this an insulin receptor number of 15–30 receptors/normal erythrocyte could be calculated.By the current results we got evidence that in the insulin/erythrocyte receptor system the terminal part of the Scatchard plot was artefactual and might not be used for the calculation procedures because it is strongly influenced by non-specific effects. Because of the fluid change from the specific to the non-specific character of binding we propose to use total ligand concentrations only up to 5 nmol/l with 4×10¹² erythrocytes/l for the investigation of specific binding on erythrocyte insulin receptors.By focussing on the initial part of the Scatchard plot curvilinearity disappeared and the character of this hormone/receptor system was reduced to one binding site with one characteristic affinity constant and a receptor concentration of one characteristic order.

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Der Einfluß der unspezifischen Bindung bei Anwendung des Scatchard Plots zur Untersuchung der Insulin/Receptor-Wechselwirkungen an Erythrocyten