Alpha-1-antitrypsin 1-5(SERPIN A1) is a secreted protein and belongs to the serpin family. Serpins bind the protease active site resulting in a major conformational rearrangement that traps the enzyme in a covalent acyl-enzyme intermediate. Mouse SERPIN A1 is a serine protease inhibitor whose targets include elastase,plasmin, thrombin, trypsin, chymotrypsin, and plasminogen activator. Defects in this gene can cause emphysema orliver disease. Several transcript variants encoding the same protein have been found for this gene.
Serpin A1a is also known as alpha-1-antitrypsin, is a member of the serpin superfamily of serine proteinase inhibitors that are involved in the regulation of a number of proteolytic processes. Its primary target is elastase, but it also has a moderate affinity for plasmin and thrombin.