Bildung von oligomeren Formen des Insulinrezeptors durch intramolekularen Disulfidaustausch. Beteiligung von maskierten SH-Gruppen: Involvement of Masked Sulfhydryl Groups

H. Krämer, A. Deger, R. Koch, R. Rapp, M. Hinz, U. Weber

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Insulin receptors from rat liver membranes were labelled with a 125I-labelled photo-reactive insulin analogue or by iodination using lactoperoxidase and analysed by sodium dodecyl sulfate Polyacrylamide gel electrophoresis. Under nonreducing conditions different receptor forms with Mr 400 000 (α2β2), 360000 (α2/ββ) 330 000 (α2 β β), 320 000 (α2β), 280 000 (α2 β') 240000 (α2), 210 000 (αß), 165 000 (αß') and 115 000 (ce) were detected. The subunit composition of these receptor forms was determined by two-dimensional sodium dodecyl sulfate Polyacrylamide gel electrophoresis in the absence and presence of dithioerythritol. During denaturation in sodium dodecyl sulfate in the absence of reductants, the Mr 400 000 receptor form (α2β2) was converted into the Mr 320 000 (α2 β) and Mr 240 000 (α2) receptor form. This conversion was prevented either by N-ethylmaleimide, oxidants, or low pH. In contrast, alkylation of the receptor with N-ethylmaleimide under non-denaturing conditions did not prevent the appearance of intermediate-sized receptor forms. Furthermore, the inhibition of receptor cleavage by N-ethylmaleimide during denaturation was also observed when the amount of free sulfhydryl groups was reconstituted by the addition of an unlabelled and non-alkylated receptor sample to the alkylated and photoaffinity-la-belled receptor. These results suggest, that the generation of different oligomeric receptor forms detected by sodium dodecyl sulfate Polyacrylamide gel electrophoresis is due at least in part to the cleavage of one or both β-subunits from the insulin receptor. This cleavage is the result of an intramolecular sulfhydryl-disulfide exchange involving masked sulfhydryl groups of the receptor itself which are uncovered by sodium dodecyl sulfate.

Original languageEnglish (US)
Pages (from-to)471-480
Number of pages10
JournalBiological Chemistry Hoppe-Seyler
Volume368
Issue number1
DOIs
StatePublished - 1987

Keywords

  • Insulin receptor oligomeric forms
  • effect of insulin
  • photoaffinity labelling
  • subunit composition
  • sulfhydryl-disulfid exchange

ASJC Scopus subject areas

  • Biochemistry

Fingerprint

Dive into the research topics of 'Bildung von oligomeren Formen des Insulinrezeptors durch intramolekularen Disulfidaustausch. Beteiligung von maskierten SH-Gruppen: Involvement of Masked Sulfhydryl Groups'. Together they form a unique fingerprint.

Cite this