| Type: | Family | Name: | Proteinase inhibitor I20 |
| Description: | Members of the potato peptidase inhibitor II family are proteinase inhibitors that belong to MEROPS inhibitor family I20, clan IA and are restricted to plants. They inhibit serine peptidases belonging to MEROPS peptidase family S1 [] (). They have a multidomain structure [], which permits circular permutation of the sequences. It was been shown that some naturally occurring Pin2 proteins, have an `ancestral' circularly permuted structure []. Circular permutation/ rearrangements of sequences has also been observed between species, such as favin from Vicia fabaand the lectin concanavalin A from Canavalia ensiformis[] or amongst members of the plant aspartyl proteinases and human lung surfactant proteins []. This family of proteinase inhibitors are present in seeds, leaves and other organs. Perhaps the best known representatives are the wound-induced proteinase inhibitors [, ], which contain up to eight sequence-repeats (the `IP repeats'). The sequence of the IP repeats is quite variable, only the cysteines constituting the four disulphide bridges and a single proline residue are conserved throughout all the known repeat sequences. The structure of the proteinase inhibitor complex is known []. | Short Name: | Prot_inh_I20 |
