Effect of pretreatments (imprinting) with different concentrations of insulin on insulin binding of nuclear envelope and plasma membrane in Tetrahymena.

About 4 h following treatment with 10(-6) - 10(-10) M insulin (imprinting) there was a down-regulation both in the plasma membrane and in the nuclear envelope of Tetrahymena, i.e. there was a decrease in the binding value related to the control. In each concentration tested the imprinting resulted in increased FITC-insulin binding after 24 and 48 h of treatment; the imprinting was independent of the concentrations. In the case of the plasma membrane the power of binding was directly proportional to the increase of the hormone concentration participating in the imprinting. For the nuclear envelope the optimal concentration was 10(-8) M. At very low concentrations (10(-10) M) the binding resulting in imprinting was insignificant in the plasma membrane but it was still present in the nucleus.