page_title: 3C-like protease
section_title: Function
hierarchical_section_title: 3C-like protease / Function
caption_attribution_description: English: Table of substrate specificities that are common among all coronavirus 3CL proteases (3CLpro). Profiling of substrate specificities of 3C-like proteases from group 1, 2a, 2b, and 3 coronaviruses.
context_page_description: The 3C-like protease, formally known as C30 Endopeptidase, is the main protease found in coronaviruses. It cleaves the coronavirus polyprotein at eleven conserved sites. It is a cysteine protease and a member of the PA clan of proteases. It has a cysteine-histidine catalytic dyad at its active site and cleaves a Gln– peptide bond.
  The Enzyme Commission refers to this family as SARS coronavirus main proteinase. The 3CL protease corresponds to coronavirus nonstructural protein 5. The "3C" in the common name refers to the 3C protease which is a homologous protease found in picornaviruses.
context_section_description: The 3C-like protease is able to catalytically cleave a peptide bond between a glutamine at position P1 and a small amino acid (serine, alanine, or glycine) at position P1'. The SARS coronavirus 3CLpro can for instance self-cleave the following peptides:
  TSAVLQ-SGFRK-NH2 and SGVTFQ-GKFKK are the two peptides corresponding to the two self-cleavage sites of the SARS 3C-like proteinase
  The protease is important in the processing of the coronavirus replicase polyprotein (P0C6U8). It is the main protease in coronaviruses and corresponds to nonstructural protein 5 (nsp5). It cleaves the coronavirus polyprotein at 11 conserved sites. The 3CL protease has a cysteine-histidine catalytic dyad at its active site. The sulfur of the cysteine acts as a nucleophile and the imidazole ring of the histidine as a general base.
caption: Substrate specificities that are common among all coronavirus 3CL proteases
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