Family

Proteinase inhibitor I1, Kazal-type, metazoa (IPR001239)

Short name: Prot_inh_Kazal-m

Overlapping homologous superfamilies

Family relationships

None.

Description

This family of Kazal eukaryotic proteinase inhibitors, belongs to MEROPS inhibitor family I1, clan IA. They inhibit serine peptidases of the S1 family (IPR001254) [PMID: 14705960]. They are restricted to the metazoa (arthropoda and chordata), and includes a single exception in the alveolata (apicomplexa). No members are found in nematodes, fungi or plants.

Kazal inhibitors, which inhibit a number of serine proteinases (such as trypsin and elastase), belong to family of proteins that includes pancreatic secretory trypsin inhibitor; avian ovomucoid; acrosin inhibitor; and elastase inhibitor. These proteins contain between 1 and 7 Kazal-type inhibitor repeats [PMID: 6699915, PMID: 3828298].

The structure of the Kazal repeat includes a large quantity of extended chain, 2 short alpha-helices and a 3-stranded anti-parallel beta sheet [PMID: 6699915].The inhibitor makes 11 contacts with its enzyme substrate: unusually, 8 of these important residues are hypervariable [PMID: 3828298]. Altering the enzyme-contact residues, and especially that of the active site bond, affects the the strength of inhibition and specificity of the inhibitor for particular serine proteinases [PMID: 3828298, PMID: 7046785].

GO terms

Biological Process

No terms assigned in this category.

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.
PRINTS