6FFA:
reference: Irreversible inactivation of ISG15 by a viral leader protease enables alternative infection detection strategies., Swatek KN, Aumayr M, Pruneda JN, Visser LJ, Berryman S, Kueck AF, Geurink PP, Ovaa H, van Kuppeveld FJM, Tuthill TJ, Skern T, Komander D, Proc Natl Acad Sci U S A. 2018 Mar 6;115(10):2371-2376. doi:, 10.1073/pnas.1710617115. Epub 2018 Feb 20. PMID: 29463763

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