Family C33


Summary Holotypes Alignment Tree Genomes Structure Literature Architecture

Summary for family C33

Family type peptidaseC33.001 - equine arteritis virus Nsp2-type cysteine peptidase (equine arteritis virus), MEROPS Accession MER0001422 (peptidase unit: 259-340)
Content of familyPeptidase family C33 contains a viral polyprotein-processing endopeptidase.
History Identifier created: Perspect.Drug Discov.Des. 6:1-11 (1996)
Catalytic typeCysteine
Active site residuesC270 H332 
Active siteCatalytic Cys and His residues have been identified by mutagenesis (Snijder et al., 1995) (see the Alignment).
Activities and specificitiesThere is indirect evidence that Nsp2-type cysteine peptidase (C33.001) cleaves between two Gly residues (Ziebuhr et al., 2004). Cleavage is rapid in cis and very slow in trans (Snijder et al., 1995).
Molecular structure
Basis of clan assignmentActive site residues for members of this family and family C1 occur in the same order in the sequence: C, H.
Distribution of family Bacteria -  
Archaea -  
Protozoa -  
Fungi -  
Plants -  
Animals -  
Viruses details  
Biological functionsNsp2-type cysteine peptidase is the most C-terminal of three peptidase domains in the N-terminal 500 residues of the arterivirus ORF1a protein. It assists the Nsp4 main peptidase (S32.001) in the proteolytic maturation of the replicase proteins through cleavage of the Nsp2Nsp3 site, regulating the processing of the ORF1a protein downstream of Nsp2 (Snijder et al., 1996; Wassenaar et al., 1997). In the presence of Nsp2, Nsp4 will cleave the Nsp4Nsp5 site at its C-terminus. However, in its absence, cleavage instead occurs at the Nsp5Nsp6 and Nsp6Nsp7 sites (Wassenaar et al., 1997).
ReviewsGorbalenya et al. (2004)
Statistics for family C33Sequences:14
Identifiers with PDB entries:1
Downloadable files Sequence library (FastA format)
Sequence alignment (FastA format)
Phylogenetic tree (Newick format)
Other databases INTERPRO IPR008743
PFAM PF05412
Peptidases and Homologues MEROPS ID Structure
equine arteritis virus Nsp2-type cysteine peptidaseC33.001Yes
Family C33 unassigned peptidasesunassigned-