Cys 786 and Cys 776 in the posttranslational processing of the insulin and IGF-I receptors

D. Maggi, R. Cordera

Research output: Contribution to journalArticlepeer-review


The extracellular regions of insulin and IGF-I receptors (IR and IGF-IR) contain fibronectin type III repeats with cysteine residues potentially involved in S=S bond. In this report we show that Cys 786 in the IR and the corresponding Cys 776 in the IGF-IR regulate proreceptor dimerization with high specificity. Both C786S insulin and C776S IGF-I proreceptors reach the monomeric 210-kDa step, but do not proceed further. Mature IRC786S and IGF-IRC776S expression on plasmamembrane is abolished. No retention of C786S IR precursor was detected in the endoplasmic reticulum, which is degraded by a nonlysosomal mechanism. The rearrangement of the remaining cysteines in the insulin receptor β subunit ectodomain does not rescue dimerization of C786S insulin proreceptor. As observed in other transmembrane receptors, iuxtamembrane cysteines, specifically Cys 786 in the IR and Cys 776 in the IGF-IR, are critical for correct processing of proreceptors.

Original languageEnglish
Pages (from-to)836-841
Number of pages6
JournalBiochemical and Biophysical Research Communications
Issue number3
Publication statusPublished - 2001


  • β subunit ectodomain
  • Dimerization
  • Extracellular cysteine
  • IGF-I receptor
  • Insulin receptor

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology


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