alpha-1-antichymotrypsin; ACT; cell growth-inhibiting gene 24/25 protein; Serpin A3 (SERPINA3, AACT, GIG24, GIG25)

Function

• physiological function is unclear
• inhibits neutrophil cathepsin G & mast cell chymase, both of which can convert angiotensin-1 to the active angiotensin-2
• interacts with DNAJC1

Structure

• the reactive center loop (RCL) extends out from the body of the protein & directs binding to the target protease
• the protease cleaves the serpin at the reactive site within the RCL, establishing a covalent linkage between the carboxyl group of the serpin reactive site & the Ser hydroxyl of the protease
• resulting inactive serpin-protease complex is highly stable
• belongs to the serpin family

Compartment

• secreted
• occurs normally in bronchial secretions

Expression

• plasma
• synthesized in the liver
• concentration increases in the acute phase of inflammation or infection. found in the amyloid

Pathology

• found in senile plaques of patients with Alzheimer's disease, thus may be secreted by neurons, glial cells, or the choroid epithelium

Notes

• alpha-1-antichymotrypsin can bind DNA
• uncertain whether Met-1 or Met-4 is the initiator

More general terms

• acute phase protein
• inter alpha globulin
• serine protease inhibitor; serpin
• glycoprotein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=12
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:12; -.
• OMIM: https://mirror.omim.org/entry/107280
• UniProt: http://www.uniprot.org/uniprot/P01011.html