Although its physiological function is unclear, it can inhibit neutrophil cathepsin G and mast cell chymase, both of which can convert angiotensin-1 to the active angiotensin-2. Belongs to the serpin family. Plasma. Synthesized in the liver. Like the related alpha-1-antitrypsin, its concentration increases in the acute phase of inflammation or infection. Found in the amyloid plaques from the hippocampus of Alzheimer disease brains. 3 alternatively spliced human isoforms have been reported. Note: This description may include information from UniProtKB.
Biological Process: acute-phase response; negative regulation of endopeptidase activity; negative regulation of peptidase activity; response to bacterium; response to cytokine; response to peptide hormone