Specificity of insulin binding by plasma and nuclear membrane receptors in Tetrahymena: similarities and dissimilarities at the two levels.

The plasma membrane and nuclear envelope of Tetrahymena are equally able to bind insulin both specifically and otherwise. Primary interaction with exogenous insulin (imprinting) accounted for an increase in the specificity of binding which became even more pronounced in the distant offspring generations of the imprinted cells. Virgin Tetrahymena cells not imprinted with insulin showed a greater specificity of insulin binding at the nuclear than at the plasma membrane level. This difference became equalized under the influence of imprinting with exogenous insulin which increased the specificity of binding at the plasma membrane level.