Family C4
Summary for family C4
| Name | Peptidase family C4 (NIa protease family) |
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| Family type peptidase | C04.001 - nuclear-inclusion-a peptidase (plum pox virus) (plum pox virus), MEROPS Accession MER0001785 (peptidase unit: 2049-2293) |
| Content of family | Peptidase family C4 contains cysteine endopeptidases of viruses. |
| History |
Identifier created: Biochem.J. 290:205-218 (1993)
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| Catalytic type | Cysteine |
| Active site residues | H2096 D2131 C2201 |
| Active site | There is a catalytic triad, His/Asp/Cys (Dougherty et al., 1989). |
| Activities and specificities | There is a preference for cleavage of Gln Gly bonds in the processing of the viral polyprotein, similar to that in family C3. |
| Inhibitors | No specific inhibitors of peptidases in this family have been described at the time of writing, but there is inhibition by general thiol-blocking compounds including TLCK and TPCK. |
| Molecular structure | The structure of the tobacco etch virus enzyme (Phan et al., 2002) shows that the molecules of the peptidases in family C4, like others in clan PA, contain a pair of beta-barrels at right-angles, with the catalytic residues between them. |
| Clan | PA |
| Subclan | PA(C) |
| Basis of clan assignment | Active site residues for members of this family and family S1 occur in the same order in the sequence: H, D, C/S. |
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Distribution of family
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Bacteria |
details |
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Archaea |
- |
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Protozoa |
- |
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Fungi |
- |
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Plants |
- |
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Animals |
- |
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Viruses |
details |
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| Biological functions | The type peptidase of family C4 is nuclear-inclusion-a endopeptidase (plum pox virus), also known as the NIa protease.The NIa proteases are required for the processing of the potyviral proproteins. |
| Pharmaceutical and biotech relevance | Because of its stringent cleavage specificity, tobacco etch virus NIa protease has proved to be a valuable reagent for cleavage of recombinant fusion proteins at glutaminyl bonds (e.g. Kapust et al., 2002). |
| Statistics for family C4 | Sequences: | 214 |
| Identifiers: | 14 |
| Identifiers with PDB entries: | 1 |
| Downloadable files |
Sequence library (FastA format) |
| Sequence alignment (FastA format) |
| Phylogenetic tree (Newick format) |
| Peptidases and Homologues |
MEROPS ID |
Structure |
| nuclear-inclusion-a peptidase (plum pox virus) | C04.001 | - |
| potato virus Y-type NIa peptidase | C04.002 | - |
| tobacco vein mottling virus-type NIa peptidase | C04.003 | - |
| tobacco etch virus NIa peptidase | C04.004 | Yes |
| Ornithogalum mosaic virus NIa peptidase | C04.005 | - |
| yam mosaic virus NIa peptidase | C04.006 | - |
| shallot potyvirus NIa peptidase | C04.007 | - |
| bean yellow mosaic virus-type NIa peptidase | C04.008 | - |
| Papaya ringspot virus NIa peptidase | C04.009 | - |
| pea seed-borne mosaic virus NIa peptidase | C04.010 | - |
| Johnson grass mosaic virus NIa peptidase | C04.011 | - |
| rye grass mosaic virus NIa peptidase | C04.012 | - |
| sweet potato mild mottle virus NIa peptidase | C04.013 | - |
| potato virus A NIa peptidase | C04.014 | - |
| Family C04 non-peptidase homologues | non-peptidase homologue | - |
| Family C04 unassigned peptidases | unassigned | Yes |
