6i3z

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Fab fragment of an antibody selective for wild-type alpha-1-antitrypsin in complex with its antigen

Structural highlights

6i3z is a 4 chain structure with sequence from Homo sapiens and Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:X-ray diffraction, Resolution 3.1Å
Ligands:NA, SO4
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Disease

A1AT_HUMAN Defects in SERPINA1 are the cause of alpha-1-antitrypsin deficiency (A1ATD) [MIM:613490. A disorder whose most common manifestation is emphysema, which becomes evident by the third to fourth decade. A less common manifestation of the deficiency is liver disease, which occurs in children and adults, and may result in cirrhosis and liver failure. Environmental factors, particularly cigarette smoking, greatly increase the risk of emphysema at an earlier age.[1] [2] [3]

Function

A1AT_HUMAN Inhibitor of serine proteases. Its primary target is elastase, but it also has a moderate affinity for plasmin and thrombin. Irreversibly inhibits trypsin, chymotrypsin and plasminogen activator. The aberrant form inhibits insulin-induced NO synthesis in platelets, decreases coagulation time and has proteolytic activity against insulin and plasmin.[:][4] [5] Short peptide from AAT: reversible chymotrypsin inhibitor. It also inhibits elastase, but not trypsin. Its major physiological function is the protection of the lower respiratory tract against proteolytic destruction by human leukocyte elastase (HLE).[:][6] [7]

Publication Abstract from PubMed

The alpha-1-antitrypsin (or alpha-1-antitrypsin, A1AT) Z variant is the primary cause of severe A1AT deficiency and forms polymeric chains that aggregate in the endoplasmic reticulum of hepatocytes. Around 2%-5% of Europeans are heterozygous for the Z and WT M allele, and there is evidence of increased risk of liver disease when compared with MM A1AT individuals. We have shown that Z and M A1AT can copolymerize in cell models, but there has been no direct observation of heteropolymer formation in vivo. To this end, we developed a monoclonal antibody (mAb2H2) that specifically binds to M in preference to Z A1AT, localized its epitope using crystallography to a region perturbed by the Z (Glu342Lys) substitution, and used Fab fragments to label polymers isolated from an MZ heterozygote liver explant. Glu342 is critical to the affinity of mAb2H2, since it also recognized the mild S-deficiency variant (Glu264Val) present in circulating polymers from SZ heterozygotes. Negative-stain electron microscopy of the Fab2H2-labeled liver polymers revealed that M comprises around 6% of the polymer subunits in the MZ liver sample. These data demonstrate that Z A1AT can form heteropolymers with polymerization-inert variants in vivo with implications for liver disease in heterozygous individuals.

Intrahepatic heteropolymerization of M and Z alpha-1-antitrypsin.,Laffranchi M, Elliston EL, Miranda E, Perez J, Ronzoni R, Jagger AM, Heyer-Chauhan N, Brantly ML, Fra A, Lomas DA, Irving JA JCI Insight. 2020 Jul 23;5(14). pii: 135459. doi: 10.1172/jci.insight.135459. PMID:32699193[8]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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Citations
5 reviews cite this structure
Post-Translational Modifications of Circulating Alpha-1-Antitrypsin Protein.
Lechowicz et al. (2020)
4 more
9 other articles
No citations found

See Also

References

  1. ↑ Seyama K, Nukiwa T, Takabe K, Takahashi H, Miyake K, Kira S. Siiyama (serine 53 (TCC) to phenylalanine 53 (TTC)). A new alpha 1-antitrypsin-deficient variant with mutation on a predicted conserved residue of the serpin backbone. J Biol Chem. 1991 Jul 5;266(19):12627-32. PMID:1905728
  2. ↑ Holmes MD, Brantly ML, Fells GA, Crystal RG. Alpha 1-antitrypsin Wbethesda: molecular basis of an unusual alpha 1-antitrypsin deficiency variant. Biochem Biophys Res Commun. 1990 Aug 16;170(3):1013-20. PMID:2390072
  3. ↑ Graham A, Kalsheker NA, Bamforth FJ, Newton CR, Markham AF. Molecular characterisation of two alpha-1-antitrypsin deficiency variants: proteinase inhibitor (Pi) Null(Newport) (Gly115----Ser) and (Pi) Z Wrexham (Ser-19----Leu). Hum Genet. 1990 Oct;85(5):537-40. PMID:2227940
  4. ↑ Tanaka N, Sekiya S, Takamizawa H, Kato N, Moriyama Y, Fujimura S. Characterization of a 54 kDa, alpha 1-antitrypsin-like protein isolated from ascitic fluid of an endometrial cancer patient. Jpn J Cancer Res. 1991 Jun;82(6):693-700. PMID:1906855
  5. ↑ Niemann MA, Narkates AJ, Miller EJ. Isolation and serine protease inhibitory activity of the 44-residue, C-terminal fragment of alpha 1-antitrypsin from human placenta. Matrix. 1992 Jun;12(3):233-41. PMID:1406456
  6. ↑ Tanaka N, Sekiya S, Takamizawa H, Kato N, Moriyama Y, Fujimura S. Characterization of a 54 kDa, alpha 1-antitrypsin-like protein isolated from ascitic fluid of an endometrial cancer patient. Jpn J Cancer Res. 1991 Jun;82(6):693-700. PMID:1906855
  7. ↑ Niemann MA, Narkates AJ, Miller EJ. Isolation and serine protease inhibitory activity of the 44-residue, C-terminal fragment of alpha 1-antitrypsin from human placenta. Matrix. 1992 Jun;12(3):233-41. PMID:1406456
  8. ↑ Laffranchi M, Elliston EL, Miranda E, Perez J, Ronzoni R, Jagger AM, Heyer-Chauhan N, Brantly ML, Fra A, Lomas DA, Irving JA. Intrahepatic heteropolymerization of M and Z alpha-1-antitrypsin. JCI Insight. 2020 Jul 23;5(14). pii: 135459. doi: 10.1172/jci.insight.135459. PMID:32699193 doi:http://dx.doi.org/10.1172/jci.insight.135459

Contents


PDB ID 6i3z

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