<p>This domain is usually indicative of serine protease inhibitors that belong to Merops inhibitor families: I1, I2, I17 and I31. However, kazal-like domains are also seen in the extracellular part of agrins, which are not known to be protease inhibitors. Kazal domains often occur in tandem arrays and have a central alpha-helix, a short two-stranded antiparallel beta-sheet and several disulphide bonds [<cite idref="PUB00026760"/>, <cite idref="PUB00026997"/>, <cite idref="PUB00028059"/>]. The amino terminal segment of this domain binds to the active site of its target proteases, thus inhibiting their function.</p> Protease inhibitor, Kazal-type