Nuclear proteasomes carry a constitutive posttranslational modification which derails SDS-PAGE (but not CTAB-PAGE)

David S. Pitcher, Kate M J De Mattos-Shipley, Ziming Wang, Konstantinos Tzortzis, Katerina Goudevenoua, Helen Flynn, George Bohn, Amin Rahemtulla, Ambrosius P. Snijders, Anastasios Karadimitris, Maurits F. Kleijnen*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

We report that subunits of human nuclear proteasomes carry a previously unrecognised, constitutive posttranslational modification. Subunits with this modification are not visualised by SDS-PAGE, which is used in almost all denaturing protein gel electrophoresis. In contrast, CTAB-PAGE readily visualises such modified subunits. Thus, under most experimental conditions, with identical samples, SDS-PAGE yielded gel electrophoresis patterns for subunits of nuclear proteasomes which were misleading and strikingly different from those obtained with CTAB-PAGE. Initial analysis indicates a novel modification of a high negative charge with some similarity to polyADP-ribose, possibly explaining compatibility with (positively-charged) CTAB-PAGE but not (negatively-charged) SDS-PAGE and providing a mechanism for how nuclear proteasomes may interact with chromatin, DNA and other nuclear components.
Original languageEnglish
Pages (from-to)2222
Number of pages2228
JournalBiochimica et Biophysica Acta (BBA)
Volume1844
Issue number12
Publication statusPublished - 1 Sep 2014

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