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Reader Domain Proteins

SARS-CoV-2 Related Protease Assays

Reaction Biology developed assays to investigate the inhibition of proteases that are essential for the replication cycle of SARS-CoV-2, the novel coronavirus responsible for COVID-19.

These assays are being offered to enable timely discovery and development of COVID-19 therapeutics:

The Role of Proteases in the SARS-CoV-2 Replication Cycle

Proteases play a critical role in the life cycle of SARS-CoV-2. Host proteases Furin and TMPRSS2 play a role in the pathogenesis and replication of respiratory viruses and cleave the spike protein to enable membrane fusion for virus entry. Cathepsin L further primes the spike protein in the acidic environment of endosomes. PLpro and Mpro are viral proteases required for virus replication. They proteolytically process the polyprotein, which is a prerequisite for virus assembly. PLpro is also known to interfere with the anti-viral immune response of the host cell.


Furin is a serine endoprotease necessary for the proteolytic processing of proteins within the secretory pathway, including viral glycoproteins. Furin is a proprotein convertase (PPC) that was found to preactivate the SARS-CoV-2 spike beside the protease TMPRSS2. The protease enhances entry into cells and thus is a potential drug target for the inhibition of virus replication1.

Furin assay data sheet

Cathepsin L

Cathepsin L is an endosomal cysteine protease. It mediates cleavage of the coronavirus surface spike glycoprotein S1 subunit. Cleavage of the S1 subunit is required for coronavirus entry into host cells, endosome membrane fusion of the virus and the host cell, and viral RNA release 2.

Cathepsin L assay data sheet


The papain-like protease (PLpro) is responsible for cleavage of the coronavirus poly-protein necessary for virus assembly. PLpro also suppresses the host innate immune through the reversal of ubiquitination and ISGylation events. Inhibition of PLpro is a potential drug target that prevents SARS-CoV-2 replication and interferes with the immune-suppressing activities of the virus3.

PLpro assay data sheet

If you are interested in screening any of our COVID related targets, please send us an email at

With the largest functional kinase activity assay panel in the industry, RBC provides kinase, epigenetic, and other profiling services to over 750 companies worldwide. RBC specializes in custom assay conditions, high quality reproducible data, and outstanding service.

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