Neuroserpin, or Serpin peptidase inhibitor, clade I (neuroserpin), member 1, is a human gene encoded by SERPINI1. It may also be known as: Neuroserpin; PI-12; Serpin I1; Peptidase inhibitor 12; PI12. The encoded protein has an amino acid length of 410 and a mass of 46.4 kDa. Other isoforms may exist. Neuroserpin is a member of the Serpin family. Homologs of this gene exist in other organisms, including: Mouse, Frog.