Alpha 1-antichymotrypsin

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Serpin peptidase inhibitor, clade A (alpha-1 antiproteinase, antitrypsin), member 3
PBB Protein SERPINA3 image.jpg
PDB rendering based on 1as4.
Available structures
PDB Ortholog search: PDBe, RCSB
Symbols SERPINA3 ; AACT; ACT; GIG24; GIG25
External IDs OMIM107280 MGI105045 HomoloGene111129 ChEMBL: 5960 GeneCards: SERPINA3 Gene
RNA expression pattern
PBB GE SERPINA3 202376 at tn.png
More reference expression data
Species Human Mouse
Entrez 12 16625
Ensembl ENSG00000273259 ENSMUSG00000066361
UniProt P01011 P29621
RefSeq (mRNA) NM_001085 NM_008458
RefSeq (protein) NP_001076 NP_032484
Location (UCSC) Chr 14:
94.59 – 94.62 Mb
Chr 12:
104.15 – 104.15 Mb
PubMed search [1] [2]

Alpha 1-antichymotrypsin (α1AC)[1] is an alpha globulin glycoprotein that is a member of the serpin superfamily. In humans, it is encoded by the SERPINA3 gene.


Alpha 1-antichymotrypsin inhibits the activity of certain enzymes called proteases, such as cathepsin G that is found in neutrophils, and chymases found in mast cells, by cleaving them into a different shape or conformation. This activity protects some tissues, such as the lower respiratory tract, from damage caused by proteolytic enzymes.[2]

This protein is produced in the liver, and is an acute phase protein that is induced during inflammation.

Clinical significance[edit]

Deficiency of this protein has been associated with liver disease. Mutations have been identified in patients with Parkinson disease and chronic obstructive pulmonary disease.[3]

Alpha 1-antichymotrypsin is also associated with the pathogenesis of Alzheimer's disease as it enhances the formation of amyloid-fibrils in this disease.[2]


Alpha 1-antichymotrypsin has been shown to interact with DNAJC1.[4]


  1. ^ Logan, Carolynn M.; Rice, M. Katherine (1987). Logan's Medical and Scientific Abbreviations. Philadelphia: J. B. Lippincott Company. p. 3. ISBN 0-397-54589-4. 
  2. ^ a b Kalsheker N (1996). "Alpha 1-antichymotrypsin". Int. J. Biochem. Cell Biol. 28 (9): 961–4. doi:10.1016/1357-2725(96)00032-5. PMID 8930118. 
  3. ^ "Entrez Gene: SERPINA3 serpin peptidase inhibitor, clade A (alpha-1 antiproteinase, antitrypsin), member 3". 
  4. ^ Kroczynska B, Evangelista CM, Samant SS, Elguindi EC, Blond SY (March 2004). "The SANT2 domain of the murine tumor cell DnaJ-like protein 1 human homologue interacts with alpha1-antichymotrypsin and kinetically interferes with its serpin inhibitory activity". J. Biol. Chem. 279 (12): 11432–43. doi:10.1074/jbc.M310903200. PMC 1553221. PMID 14668352. 

Further reading[edit]

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