Proteinase inhibitor I13, potato inhibitor I (IPR000864)

Short name: Prot_inh_pot1

Overlapping homologous superfamilies

Family relationships



This family of proteinase inhibitors belong to MEROPS inhibitor family I13, clan IG. They inhibit peptidases of the S1 (IPR001254) and S8 (IPR000209) families [PMID: 14705960]. Potato inhibitor type I sequences are not solely restricted to potatoes but are found in other plant species for example: barley endosperm chymotrypsin inhibitor [PMID: 3106042], and pumpkin trypsin inhibitor. Apart from leeches, e.g.Hirudo medicinalis (Medicinal leech), homologues are not found in metazoa [PMID: 3519213]. In general, the proteins have retained a specificity towards chymotrypsin-like and elastase-like proteases. Structurally these inhibitors are small (60 to 90 residues) and in contrast with other families of protease inhibitors, they lack disulphide bonds. The inhibitor is a wedge-shaped molecule, its pointed edge formed by the protease-binding loop, which contains the scissile bond. The loop binds tightly to the protease active site, subsequent cleavage of the scissile bond causing inhibition of the enzyme [PMID: 3519213].

The inhibitors (designated type I and II) are synthesised in potato tubers, increasing in concentration as the tuber develops. Synthesis of the inhibitors throughout the plant is also induced by leaf damage; this systemic response being triggered by the release of a putative plant hormone.

Examples found in the bacteria and archaea are probable false positives.

GO terms

Biological Process

GO:0009611 response to wounding

Molecular Function

GO:0004867 serine-type endopeptidase inhibitor activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE patterns