Analysis of three human interleukin 5 structures suggests a possible receptor binding mechanism
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Updated: Oct 30, 2026

An ELISA Based Binding and Competition Method to Rapidly Determine Ligand-receptor Interactions
Published on: March 14, 2016
J L Verschelde1, C Ampe, Y Guisez
1Flanders' Interuniversity Institute for Biotechnology, Department of Medical Protein Research, University Ghent, Faculty of Medicine, Gent, Belgium.
Abstract:
We compared three crystal structures of human interleukin 5 (hIL5) expressed in either E. coli (hIL5E.coli), Sf9 cells (hIL5sf9) or Drosophila cells (hIL5Drosophila). The dimeric hIL5 structures show subtle but significant conformational differences which are probably a consequence of the different crystallization conditions trapping this protein into one of two states. We refer to these two distinct conformations as the 'open' and 'tight' state, according to the packing around the cleft between the two subunits. We hypothesize that these two stable conformational states reflect the structure of the free or receptor bound hIL5.
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