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: Isolation of functional alpha beta heterodimers from the purified human placental alpha 2 beta 2 heterotetrameric insulin receptor complex. A structural basis for insulin binding heterogeneity.
    Author: Sweet LJ, Morrison BD, Pessin JE.
    Journal: J Biol Chem; 1987 May 25; 262(15):6939-42. PubMed ID: 3294822.
    Abstract:
    To investigate the role of subunit communication in the insulin binding and tyrosine-specific protein kinase activities of the purified human placental insulin receptor, we have developed the methodology to isolate a functional alpha beta heterodimeric insulin receptor complex from the native alpha 2 beta 2 heterotetrameric disulfide-linked state. The dissociation of the alpha 2 beta 2 heterotetrameric insulin receptor into an alpha beta heterodimer was found to be approximately 50% efficient by treatment with alkaline pH (8.75) and dithiothreitol (2 mM). Removal of the dithiothreitol and pH neutralization (pH 7.60) by rapid Sephadex G-50 gel filtration resulted in the preservation of tracer insulin binding activity. The nondissociated alpha 2 beta 2 heterotetrameric and alpha beta heterodimeric insulin receptor complexes could then be effectively separated by Bio-Gel A-1.5m gel filtration. Scatchard analyses of insulin binding to the alpha 2 beta 2 heterotetrameric control or dithiothreitol-treated but nondissociated alpha 2 beta 2 heterotetrameric insulin receptor complexes demonstrated a curvilinear binding isotherm with a maximum of 1 mol of insulin bound/mol of alpha 2 beta 2 heterotetrameric complex. However, binding analyses performed on the isolated alpha beta heterodimeric complex yielded a nearly linear binding curve also, with 1 mol of insulin bound/mol of alpha beta heterodimeric complex at saturation. These data demonstrate that the insulin half-site binding reactivity observed in the alpha 2 beta 2 heterotetrameric insulin receptor complex results from either an asymmetric assembly of identical alpha beta heterodimers or from absolute negative cooperativity.
    [Abstract] [Full Text] [Related] [New Search]