| Type: | Domain | Name: | Peptidase C3A/C3B, picornaviral |
| Description: | Cysteine peptidases have characteristic molecular topologies, which can be seen not only in their three-dimensional structures, but commonly also in the two-dimensional structures. These are peptidases in which the nucleophile is the sulphydryl group of a cysteine residue. Cysteine proteases are divided into clans (proteins which are evolutionary related), and further sub-divided into families, on the basis of the architecture of their catalytic dyad or triad []. This signature defines cysteine peptidases belong to MEROPS peptidase family C3 (picornain, clan PA(C)), subfamilies C3A and C3B. The protein fold of this peptidase domain for members of this family resembles that of the serine peptidase, chymotrypsin [], the type example for clan PA.Picornaviral proteins are expressed as a single polyprotein which is cleaved by the viral C3 cysteine protease. The poliovirus polyprotein is selectively cleaved between the Gln-|-Gly bond. In other picornavirus reactions Glu may be substituted for Gln, and Ser or Thr for Gly. | Short Name: | Peptidase_C3A/C3B_picornavir |
