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: An alternative model for the binding and release of diferric transferrin by reticulocytes.
    Author: Woodworth RC, Brown-Mason A, Christensen TG, Witt DP, Comeau RD.
    Journal: Biochemistry; 1982 Aug 31; 21(18):4220-5. PubMed ID: 7126538.
    Abstract:
    The biphasic binding of diferric transferrin to reticulocytes has been reevaluated with a series of kinetic and equilibrium studies. Identical binding progress profiles were observed for reticulocytes in the presence or absence of oxygen. The relative size of the rapid initial adsorption step could be increased to ca. 65% of the total binding by stripping the cells of endogenous transferrin or reduced to 0% by preloading the cells with nonradiolabeled diferric transferrin. Preloading the cells with 125I-labeled diferric transferrin and chasing with 131I-labeled diferric transferrin revealed identical rate constants for release and binding. Scatchard plots of equilibrium binding of diferric transferrin to reticulocytes showed no significant effects of anaerobiasis or 2,4-dinitrophenol on the equilibrium binding constant or the maximum number of binding sites. The potent microtubule inhibitor nocodazole had no effect on the progress curves for transferrin binding or iron uptake by reticulocytes. It was concluded that the rapid adsorption step in the binding profile represents binding to open receptors and that the slow first-order binding phase represents binding of radiolabeled transferrin to receptors already occupied by nonlabeled endogenous transferrin as this endogenous transferrin leaves the receptors. Furthermore, this first-order binding phase, unlike iron uptake, does not require the presence of active oxidative phosphorylation. These findings are consistent with a specific desorption-adsorption model for the interaction of diferric transferrin with reticulocytes.
    [Abstract] [Full Text] [Related] [New Search]