Internalization of receptor and hormone after hormonal imprinting, as detected with colloidal gold labeled insulin in cultures of a permanent liver cell line.

The intracellular localization of internalized colloidal gold-labeled hormone differed markedly between Chang liver cells pretreated and not pretreated with insulin. While the non-imprinted cells bound little hormone in the coated pits and internalized it mainly inside smooth vesicles, the imprinted cells bound the bulk of hormone in coated pits and coated vesicles. Later the label appeared inside the lysosomes and in the imprinted cells it was abundantly present also in extra-lysosomal localizations, mainly on the nuclear membrane and inside the nucleus. These observations disclosed some new information on the internalization of the receptor-hormone complex, and on the mechanism of hormonal imprinting as well.