Background: TSG-6 (TNF-stimulated gene-6)-dependent transfer of heavy chains from inter-inhibitor onto hyaluronan is critical for ovulation. Results: A calcium ion and chelating glutamate within TSG-6 mediate formation of the covalent heavy chain-TSG-6 intermediate. Conclusion: TSG-6 transferase activity rather than hyaluronan binding drives cumulus expansion. Significance: The role of metal ions in hyaluronan-heavy chain formation has been determined.
Briggs, D. C., Birchenough, H. L., Ali, T., Rugg, M. S., Waltho, J. P., Ievoli, E., … Day, A. J. (2015). Metal Ion-dependent heavy chain transfer activity of TSG-6 mediates assembly of the cumulus-oocyte matrix. Journal of Biological Chemistry, 290(48), 28708–28723. https://doi.org/10.1074/jbc.M115.669838