E3 Ligases

E3 Ligases

Find Your E3 Ligases and Related Products

Single-subunit E3 Ligases

E3 Ligases

Multi-subunit E3 Ligase Complexes

E3 Ligase Complexes

E3 Activity Kits

E3 Activity

Accessory Proteins


TUBEs Tandem Ubiquitin Binding Entities

TUBEs Tandem Ubiquitin
Binding Entities

PROTACs and Targeted Protein Degradation

PROTACs and Targeted
Protein Degradation


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E3 Ubiquitin Ligases

As much as 5% of human genes encode E3 Ubiquitin Ligases (E3’s), with the total number of these enzymes being estimated at 600 or more. E3 Ligases are important components of the Ubiquitin Proteasome System (UPS), the master regulator of protein homeostasis that is essential for proper cellular function. As the last component of a enzymatic cascade that also consists of a ubiquitin activating enzyme (E1) and ubiquitin conjugating enzymes (E2’s), E3 Ligases selectively modify proteins by covalently attaching ubiquitin to lysine, serine, threonine or cysteine residues within the particular E3’s cognate substrate. Attaching ubiquitin to a protein (known as “ubiquitination” or “ubiquitylation”) can have profound effects on the protein’s cellular localization, protein-protein interactions and/or stability. Perhaps the most well-studied consequence of protein ubiquitination is the ATP-dependent degradation of polyubiquitinated proteins via the 26S proteasome. The biological importance of E3 Ubiquitin ligases cannot be overstated, as protein ubiquitination is crucial in signal transduction, mitophagy, DNA damage repair, inflammatory pathways, endocytosis and cell-cycle progression.

Targeted Protein Degradation is a rapidly emerging field wherein small molecule degraders (e.g. PROTAC® molecules) are used to redirect or co-opt E3 Ubiquitin Ligases to new targets (“neosubstrates”) for polyubiquitination and subsequent proteasome-mediated degradation. By redirecting the Ubiquitin-Proteasome System in this manner, disease-driving proteins that were once considered undruggable are receiving new attention.

Single-subunit E3 Ligases

These single subunit E3 ligases are capable of ubiquitinating protein substrates in vitro when supplied with ubiquitin, E1, an appropriate E2, and ATP. These include enzymes from the RING, U-box, HECT and RBR class E3’s.

CHIP/Stub1 ITCH/AIP4 Isoform 2 Parkin
cIAP-1/HIAP-2 Livin alpha/BIRC7 RNF4
cIAP-2/HIAP-1 Livin beta/BIRC7 RNF114
HOIP/RNF31 NleL Catalytic Domain  


Multi-subunit E3 Ligase Complexes

Many E3 ligases are assembled from multiple subunits, in many cases consisting of a substrate receptor, an adaptor(s), a cullin and a RING. These include enzymes from Skp-Cul1-Fbox, Elongin-Cul2/5-SOCS box, DCAF-Cul4 and others E3 classes. Some products are capable of ubiquitinating protein substrates in vitro when supplied with ubiquitin, E1, an appropriate E2, and ATP. Others are purified substrate receptors for use in binding studies.



E3 Activity Kits

E3 Activity Kits supply everything needed to perform in vitro ubiquitination reactions with a customer supplied substrate. Most kits include a control substrate with primary detection antibody for Western Blot analysis of results.

E3 Activity Kits Catalog #
CHIPUbiquitin Ligase Kit - Luciferase Substrate K-280
cIAP-1/HIAP2Ubiquitin Ligase Kit K-260
E6AP Ubiquitin Ligase Kit - S5a Substrate K-230
E6AP/E6Ubiquitin Ligase Kit - p53 Substrate K-240
ITCH/AIP4 Ubiquitin Ligase Kit K-270
Mdm2/HDM2Ubiquitin Ligase Kit - p53 Substrate K-200B
Mdm2/HDM2 Ubiquitin Ligase Kit - S5a Substrate K-210
MuRF1/TRIM63 Ubiquitin Ligase Kit - S5a Substrate K-102
RNF4 Ubiquitin Ligase Kit - di-SUMO3 Substrate K-220
XIAP Ubiquitin Ligase Kit - Diablo Substrate K-250


Accessory Proteins

Accessory proteins include E3 ligase co-factors such as kinases and heat shock proteins. Also included are E3 ligase substrates and proteins for research in aggresomal disorders.

BRD4 HSP70/HSPA1A alpha-Synuclein
HSP10/EPF HSP90 alpha Tau
HSP40/DNAJB1 Miro1/Rhot1 TDP-43/TARDBP
HSP60 PINK1 Viral HPV E6


TUBEs: Tandem Ubiquitin Binding Entities

TUBEs, Tandem Ubiquitin Binding Entities, are used for isolation and identification of ubiquitinated proteins. TUBEs display increased affinity for poly-ubiquitin moieties over the single Ubiquitin Binding Associated domain (UBA). TUBEs also display a protective effect on poly-ubiquitinated proteins, allowing for detection at relatively low levels.

TUBE Catalog #
Recombinant Human Ubiquilin 1 Tandem UBA (TUBE2) Agarose AM-130-250
Recombinant Human HR23A Tandem UBA (TUBE1) Agarose AM-125-250
Recombinant Human His6-Ubiquilin 1 Tandem UBA (TUBE2) UBE-110-250
Recombinant Human Ubiquilin 1 Tandem UBA (TUBE2) Biotin UBE-115-250
Recombinant Human His6-HR23A/Rad23A Tandem UBA (TUBE1) UBE-210-250
Recombinant Human HR23A/Rad23A Tandem UBA (TUBE1) Biotin UBE-215-25
Recombinant Human His6-Fluorescein-Tandem UBA (TUBE1) UBE-212-100


Other Resources

Ubiquitin and Ubiquitin-like Modifiers

Protocol: Determine Ubiquitin Chain Linkage

In Vitro Ubiquitin Conjugation Protocols

Boston Biochem Products and Services

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