Bowman-Birk type proteinase inhibitor
SMART accession number:SM00269
Interpro abstract (IPR000877):

Peptide proteinase inhibitors can be found as single domain proteins or as single or multiple domains within proteins; these are referred to as either simple or compound inhibitors, respectively. In many cases they are synthesised as part of a larger precursor protein, either as a prepropeptide or as an N-terminal domain associated with an inactive peptidase or zymogen. This domain prevents access of the substrate to the active site. Removal of the N-terminal inhibitor domain either by interaction with a second peptidase or by autocatalytic cleavage activates the zymogen. Other inhibitors interact direct with proteinases using a simple noncovalent lock and key mechanism; while yet others use a conformational change-based trapping mechanism that depends on their structural and thermodynamic properties.

This family of eukaryotic proteinase inhibitors, belongs to MEROPS inhibitor family I12, clan IF. They inhibit serine peptidases of the S1 family (IPR001254) [(PUBMED:14705960)].

The Bowman-Birk inhibitor family [(PUBMED:6996568)] is one of the numerous families of serine proteinase inhibitors. They have a duplicated structure and generally possess two distinct inhibitory sites. These inhibitors are primarily found in plants and in particular in the seeds of legumes as well as in cereal grains. In cereals they exist in two forms, one of which is a duplication of the basic structure [(PUBMED:3667571)]. Proteins of the Bowman-Birk inhibitor family of serine proteinase inhibitors interact with the enzymes they inhibit via an exposed surface loop that adopts the canonical proteinase inhibitory conformation. The resulting non-covalent complex renders the proteinase inactive. This inhibition mechanism is common for the majority of serine proteinase inhibitor proteins and many analogous examples are known. A particular feature of the Bowman-Birk inhibitor protein, however, is that the interacting loop is a particularly well-defined disulphide-linked short beta-sheet region [(PUBMED:11375759), (PUBMED:12325158), (PUBMED:12643767)].

GO component:extracellular region (GO:0005576)
GO function:serine-type endopeptidase inhibitor activity (GO:0004867)
Family alignment:
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There are 188 BowB domains in 159 proteins in SMART's nrdb database.

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