Table 1.

An overview of reagents or techniques (typical examples) to study proteasome activity or localization.

Classes	Examples	Activity	Localization	Cell permeability	References
Peptide-based model substrates	β1: Z-LLE-AMC, Z-LLE-NA, Ac-nLPnLD-AMC, AC-GPLD-AMC, Z- nLPnLD-aminoluciferin	Yes	No	No	Kisselev and Goldberg, 2005; Moravec et al., 2009
	β2: Bz-VGR-AMC, Boc-LRR-AMC, Z-ARR-AMC, Bz-FVR-AMC, Boc-LSTR-AMC, Ac-RLR-AMC, Z-LRR-aminoluciferin	Yes	No	No
	β5: Suc-LLVY-AMC, Z-GGL-AMC, Suc-AAF-AMC, Suc-LLVY-aminolufiferin	Yes	No	No
	Nonapeptides: LFP, LF-2	Yes	No	No	Smith et al., 2005; Jastrab et al., 2015
	FRET reporter 1	Yes	No	No	Coleman and Trader, 2018
Protein-based model substrates	Ub4(K48)-Ub-GFP-Tail, Ub8(K48)-Ub-GFP-Tail, Ub4(K63)-Ub-GFP-Tail, Ub4(K11)-Ub-GFP-Tail, Tail-GFP-Ub-Ub4(K63), Ub2(K48)-Ub2(K48)–GFP-Tail	Yes	No	No	Martinez-Fonts and Matouschek, 2016
	Poly-ubiquitinated substrate (with polyubiquitin chains and Alexa Fluor 546 dye)	Yes	No	No	Bhattacharyya et al., 2016
	Ub4(lin)-GFP-Tail	Yes	No	No	Singh Gautam et al., 2018
	UbLRad23-GFP-95	Yes	No	No	Yu et al., 2016
Fluorescently-tagged proteins	ODC-GFP, Ub-R-GFP, Ub-L-GFP	Yes	No	N/A	Li et al., 1998; Dantuma et al., 2000
	YFP-Plk1	Yes	No	N/A	Lindon and Pines, 2004
	GFP-β1i	No	Yes	N/A	Reits et al., 1997
	DQ-ovalbumin	Yes	Yes	No	Rockel et al., 2005
Deg-On system	Deg-On, eDeg-On	Yes	No	N/A	Zhao et al., 2014
Subunit specific ABPs*	β1c/ β1i- selective ABP	Yes	No	Yes	van Swieten et al., 2007
	β1i/β1c: Cy5-NC001, BodipyFL-NC001, BodipyFL-LU001c, Cy5-LU001i	Yes	No	No	de Bruin et al., 2016a,b
	β2i/β2c: BODIPY(FL)-LU112, Cy5-LU112	Yes	No	No
	β5i/β5c: BODIPY(TMR)-NC005, Cy5-LU015, BodipyFL-LU015, BodipyFL-LU015c, Cy5-LU035i	Yes	No	No
Pan-reactive ABPs*	Dansyl-Ahx3-L3-VS	Yes	Yes	Yes	Berkers et al., 2005
	BodipyFL-Ahx3-L3-VS	Yes	Yes	Yes	Berkers et al., 2007
	BodipyTMR-Ahx3-L3-VS	Yes	Yes	Yes	Verdoes et al., 2006

^*There are comprehensive summaries about these probes available in other review articles (Carmony and Kim, 2013; Hewings et al., 2017).