Insulin binding and biological activities in the FRTL-5 rat thyroid cell line

Vincenzo Trischitta, Giuseppe Damante, Daniela Foti, Sebastiano Filetti

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A cloned rat thyroid cell line (FRTL-5) was examined for both insulin binding and responsiveness. The characteristics of insulin binding to thyroid cells were similar to those observed in typical insulin target cells. The 125I-insulin binding was time and temperature dependent and Scatchard analysis suggested the presence of two major binding sites with high and low affinity constant (Kd = 1.4 × 10-10 mol/L and 1.5 × 10-9 mol/L, respectively). 125I-insulin was also internalized and degraded in a temperature-dependent manner. IGF1 was weakly effective in completing 125I-insulin binding to FRTL-5 cells (57% inhibition at 333 nmol/L), whereas noninsulin-related peptide hormones were ineffective. Exposure of FRTL-5 cells to insulin stimulated both methyl-aminoisobutyric acid (M-AIB) and 2-deoxy-D-glucose (2DG) transport. These effects were evident at 10-9 mol/L and maximal at 10-7 mol/L insulin. Maximal stimulation was three- to four-fold over basal value for both M-AIB and 2DG transport. These data suggest that insulin specifically binds to FRTL-5 cells and regulates different biological functions of this thyroid cell line.

Original languageEnglish
Pages (from-to)379-383
Number of pages5
Issue number4
Publication statusPublished - 1987

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism


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