In Vitro Ubiquitination: Self-Ubiquitination, Chain Formation, and Substrate Ubiquitination Assays.
Ubiquitination of proteins in vitro has evolved as an indispensable tool for the functional analysis of this posttranslational modification. In vitro ubiquitination is particularly helpful to study conjugation mechanisms. The efficiency of the ubiquitination reaction depends in part on the quality of the enzymes utilized. Here we introduce the assay developed in our lab to study HECT E3 ligases. It involves bacterially expressed E1, His-tagged Ube2D3 (also called UbcH5c, the best E2 for Nedd4), untagged Nedd4, and untagged ubiquitin (Ub). As tags may impair specific activity of the enzymes or even interfere with the enzymatic reaction, they should be avoided, removed, or kept to a minimal size whenever possible, unless proven to be without consequence. The protocol described here is suitable for other E3 ligases capable of forming Ub chains as pseudo-product of the enzyme reaction. It is also adapted to include substrates. In this case, substrates should be tagged and purified after the reaction is completed to allow the detection of the ubiquitinated products.
IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, Milan, 20139, Italy.
Elena
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Maspero
IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Via Adamello 16, Milan, 20139, Italy. simona.polo@ifom.eu.|Dipartimento di Oncologia ed Emato-oncologia, Università degli Studi di Milano, via Festa del Perdono 7, Milan, 20122, Italy. simona.polo@ifom.eu.
Simona
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Polo
D000818:Animals; D001681:Biological Assay / Q000379:methods*; D006801:Humans; D000075702:Nedd4 Ubiquitin Protein Ligases / Q000378:metabolism; D013379:Substrate Specificity; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D054875:Ubiquitination / Q000235:genetics / Q000502:physiology*
D025801:Ubiquitin; D000075702:Nedd4 Ubiquitin Protein Ligases; D044767:Ubiquitin-Protein Ligases
E3 ligase; In vitro assay; Nedd4; Ubiquitination