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Ligand Screening for E3 Ligase

As a leading service provider in the field of biological research and drug discovery, Creative Biolabs is fully competent and dedicated to serving one-stop PROTAC development which has become a promising strategy in the area of small molecule drug discovery. With the comprehensive advanced platform, Creative Biolabs provides global clients with ligand screening service to meet the novel drug discovery goals.


With a pronounced phenotype by removing disease-promoting proteins via ubiquitination and degradation rather than blocking them, PROTAC technology is emerging as a novel therapeutic approach with promising opportunity to target undruggable proteins. PROTAC small molecules contain a chemical linker, a target protein binding moiety, and a ligand for recruiting the degradation machinery. As bifunctional small molecules which can simultaneously bind a target protein and an E3 ligase, PROTAC can cause interaction between target protein and E3 ligase, and then target protein can be ubiquitinated and degraded by E3 ligase through proteasome. Three components are all strictly critical for the functional role of PROTAC. For E3 ligase, there are 3 classes: U-box, RING, and HECT. Human genome encodes more than 600 E3 ubiquitin ligases, which offers vast opportunities to develop various ligands for E3 ligases to promote drug discovery.

Introduction of Ligand Screening for E3 Ligase

It has been demonstrated that PROTACs with the same ligand for the target protein, but different ligands for E3 ligases display variable selectivity for target proteins and different efficiencies of target protein degradation. Herein, ligand screening for E3 ligases is decisive to determine the efficiency of PROTAC. To date, the most popular E3 ubiquitin ligases which have been successfully hijacked for use by small molecule PROTAC technology include the Von Hippel-Lindau disease tumor suppressor protein (VHL), the Mouse Double Minute 2 homologue (MDM2), the Cellular Inhibitor of Apoptosis (cIAP), and cereblon (CRBN) (see Fig.1). Creative Biolabs is dedicated for the ligand screening for E3 ligases of interest, and we offer our clients with a comprehensive series of ligand products as well as customized ligand screening service as per specific requirements to best fit your needs. We aim to provide E3 ligase ligands with high specificity and affinity to help our clients to accelerate the development of PROTACs.

Different small molecules of different E3 ligase-based PROTACs. Fig.1 Different small molecules of different E3 ligase-based PROTACs. (Gu, 2018)

Highlight Features of Our Services

  • Ph.D. level scientists and skillful technicians
  • Extensive experience and advanced platforms
  • High-quality one-stop service
  • Timely troubleshooting
  • Both design and synthesis services are available in Creative Biolabs

Creative Biolabs is dedicated to the development of small molecule PROTACs and we offer our clients with all aspects to best fit your needs to maximally promote the project progression. With advanced platform and senior scientists, we are committed to exploring and offering highly tailored ligands to fit your timeline and research budget. For more details regarding Creative Biolab's PROTAC service and a detailed quote, please feel free to contact us to assist you.


  1. Gu, S., et al. PROTACs: An Emerging Targeting Technique for Protein Degradation in Drug Discovery. Bioessays. 2018, 40(4), e1700247.
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