These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: The hepatic interleukin-6 receptor. Studies on its structure and regulation by phorbol 12-myristate 13-acetate-dexamethasone.
    Author: Pietzko D, Zohlnhöfer D, Graeve L, Fleischer D, Stoyan T, Schooltink H, Rose-John S, Heinrich PC.
    Journal: J Biol Chem; 1993 Feb 25; 268(6):4250-8. PubMed ID: 8440709.
    Abstract:
    Recombinant human 125I-interleukin-6 (IL-6) was cross-linked with the homobifunctional reagent disuccinimidyl suberate to human hepatoma cells (HepG2). Three recombinant human 125I-IL-6-containing complexes of apparent molecular masses of 100, 120, and 200 kDa were immunoprecipitated with specific antibodies to human IL-6 or to the 80-kDa IL-6 receptor subunit. We show by immunoprecipitation, peptide mapping, and by the use of a cleavable heterobifunctional cross-linker (Denny-Jaffe reagent) that different polypeptides are involved in the formation of the 100- and 120-kDa IL-6-containing complexes. The molecular compositions of the 100- and 120-kDa cross-linked complexes were identified. The 100-kDa complex consisted of one ligand and one IL-6 receptor subunit, glycoprotein 80 (gp80), whereas the 120-kDa complex was found to be composed of one ligand and a polypeptide which was immunoprecipitable with the monoclonal antibody AM64 directed against gp130. Exposure of HepG2 cells to phorbol 12-myristate 13-acetate (PMA) or PMA-dexamethasone led to an increase in the 80-kDa IL-6 receptor mRNA and functional receptor protein. Whereas treatment of HepG2 cells with PMA led to an increase in the formation of gp80.gp130.IL-6 complexes determined by cross-linking, no corresponding increase in high affinity binding sites was found. The existence of a third IL-6 receptor subunit present in limiting amounts on HepG2 cells is proposed to explain this discrepancy. Evidence is presented that the 80-kDa IL-6 receptor up-regulation by PMA-dexamethasone is caused by the depletion of protein kinase C since the protein kinase C inhibitor staurosporine mimics the effect of PMA-dexamethasone.
    [Abstract] [Full Text] [Related] [New Search]