SUPERFAMILY 1.75 HMM library and genome assignments server

CI-2 family of serine protease inhibitors superfamily

SCOP classification
Root:   SCOP hierarchy in SUPERFAMILY [ 0] (11)
Class:   Alpha and beta proteins (a+b) [ 53931] (376)
Fold:   CI-2 family of serine protease inhibitors [ 54653]
Superfamily:   CI-2 family of serine protease inhibitors [ 54654]
Families:   CI-2 family of serine protease inhibitors [ 54655] (4)

Superfamily statistics
Genomes (60) Uniprot 2013_05 PDB chains (SCOP 1.75)
Domains 619 483 40
Proteins 613 481 40

Functional annotation
General category Processes_IC
Detailed category Proteases

Function annotation of SCOP domain superfamilies

UniProtKB KeyWords (KW)

(show details)
KW termFDR (all)SDKW levelAnnotation (direct or inherited)
Cellular componentSecreted5.195e-06Moderately InformativeDirect
DomainSignal4.222e-06Least InformativeDirect
Post-translational modificationProtease inhibitor0InformativeDirect

Document: KW annotation of SCOP domains

InterPro annotation
Cross references IPR000864 SSF54654 Protein matches

This family of proteinase inhibitors belong to MEROPS inhibitor family I13, clan IG. They inhibit peptidases of the S1 and S8 families [PubMed14705960]. Potato inhibitor type I sequences are not solely restricted to potatoes but are found in other plant species for example: barley endosperm chymotrypsin inhibitor [PubMed3106042], and pumpkin trypsin inhibitor. Exceptions are found in leech's, e.g.Hirudo medicinalis (Medicinal leech), but not other metazoa [PubMed3519213]. 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 [PubMed3519213].

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.

InterPro database

PDBeMotif information about ligands, sequence and structure motifs
Cross references PDB entries
Ligand binding statistics
Nucleic-acid binding statistics
Occurrence of secondary structure elements
Occurrence of small 3D structural motifs

PDBeMotif resource

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Internal database links

Browse genome assignments for this superfamily. The SUPERFAMILY hidden Markov model library has been used to carry out SCOP domain assignments to all genomes at the superfamily level.

Alignments of sequences to 6 models in this superfamily are available by clicking on the 'Alignments' icon above. PDB sequences less than 40% identical are shown by default, but any other sequence(s) may be aligned. Select PDB sequences, genome sequences, or paste in or upload your own sequences.

Browse and view proteins in genomes which have different domain combinations including a CI-2 family of serine protease inhibitors domain.

Examine the distribution of domain superfamilies, or families, across the major taxonomic kingdoms or genomes within a kingdom. This gives an immediate impression of how superfamilies, or families, are restricted to certain kingdoms of life.

Explore domain occurrence network where nodes represent genomes and edges are domain architectures (shared between genomes) containing the superfamily of interest.

There are 6 hidden Markov models representing the CI-2 family of serine protease inhibitors superfamily. Information on how the models are built, and plots showing hydrophobicity, match emmission probabilities and insertion/deletion probabilities can be inspected.

Jump to [ Top of page · SCOP classification · InterPro annotation · PDBeMotif links · Functional annotation · UniProtKB KeyWords (KW) · Internal database links ]