This family of serine protease inhibitors has a beta-trefoil fold and inhibits trypsin and chymotrypsin [1-2].

1: Structural basis of trypsin inhibition and entomotoxicity of cospin, serine protease inhibitor involved in defense of Coprinopsis cinerea fruiting bodies. Sabotic J, Bleuler-Martinez S, Renko M, Avanzo Caglic P, Kallert S, Strukelj B, Turk D, Aebi M, Kos J, Kunzler M; J Biol Chem. 2012;287:3898-3907. PMID:22167196

2: The inhibitory properties and primary structure of a novel serine proteinase inhibitor from the fruiting body of the basidiomycete, Lentinus edodes. Odani S, Tominaga K, Kondou S, Hori H, Koide T, Hara S, Isemura M, Tsunasawa S; Eur J Biochem. 1999;262:915-923. PMID:10411656