High resolution structure of cleaved Serpin 42 Da from Drosophila melanogaster

Andrew M Ellisdon, Qingwei Zhang, Michelle A Henstridge, Travis K Johnson, Coral G Warr, Ruby HP Law, James C Whisstock

The Drosophila melanogaster Serpin 42 Da gene (previously Serpin 4) encodes a serine protease inhibitor that is capable of remarkable functional diversity through the alternative splicing of four different reactive centre loop exons. Eight protein isoforms of Serpin 42 Da have been identified to date, targeting the protease inhibitor to both different proteases and cellular locations. Biochemical and genetic studies suggest that Serpin 42 Da inhibits target proteases through the classical serpin 'suicide' inhibition mechanism, however the crystal structure of a representative Serpin 42 Da isoform remains to be determined.