CELA3B explained

Chymotrypsin-like elastase family member 3B also known as elastase-3B, protease E, or fecal elastase is an enzyme that in humans is encoded by the CELA3B gene.^{[1] [2] [3]}

Clinical literature that describes human elastase 1 activity in the pancreas or fecal material is actually referring to chymotrypsin-like elastase family member 3B (i.e. the enzyme / protein this article focuses on).^[4]

Function

Elastases form a subfamily of serine proteases that hydrolyze many proteins in addition to elastin. Humans have six elastase genes which encode the structurally similar proteins elastase 1, 2, 2A, 2B, 3A, and 3B. Unlike other elastases, elastase 3B has little elastolytic activity. Like most of the human elastases, elastase 3B is secreted from the pancreas as a zymogen and, like other serine proteases such as trypsin, chymotrypsin and kallikrein, it has a digestive function in the intestine. Elastase 3B preferentially cleaves proteins after alanine residues. Elastase 3B may also function in the intestinal transport and metabolism of cholesterol. Both elastase 3A and elastase 3B have been referred to as protease E and as elastase 1, and excretion of this protein in fecal material is frequently used as a measure of pancreatic function in clinical assays.^[3]

Clinical significance

Fecal elastase is a medical test that measures how well the pancreas is functioning.

The fecal elastase test measures the concentration of the elastase-3B enzyme found in fecal matter with an enzyme-linked immunosorbent assay (ELISA). Results of this test can give a good indication of exocrine pancreatic status, and the test is less invasive and expensive than the current "gold standard", secretin-cholecystokinin test.^[5] Levels of fecal elastase lower than 200 μg / g of stool indicate an exocrine insufficiency. Correlations between low levels and chronic pancreatitis^[6] and cancer have been reported.

Further reading

• Avilés FX, Pascual R, Salva M . Generation of a subunit III-like protein by autolysis of human and porcine proproteinase e in a binary complex with procarboxypeptidase A. . Biochem. Biophys. Res. Commun. . 163 . 3 . 1191–6 . 1989 . 2675835 . 10.1016/0006-291X(89)91104-2 . etal.
• Wendorf P, Geyer R, Sziegoleit A, Linder D . Localization and characterization of the glycosylation site of human pancreatic elastase 1. . FEBS Lett. . 249 . 2 . 275–8 . 1989 . 2737288 . 10.1016/0014-5793(89)80640-4 . 8342954 .
• Moulard M, Kerfelec B, Mallet B, Chapus C . Identification of a procarboxypeptidase A-truncated protease E binary complex in human pancreatic juice. . FEBS Lett. . 250 . 2 . 166–70 . 1989 . 2753124 . 10.1016/0014-5793(89)80712-4 . free .
• Guy-Crotte O, Barthe C, Basso D . Characterization of two glycoproteins of human pancreatic juice: P35, a truncated protease E and P19, precursor of protein X. . Biochem. Biophys. Res. Commun. . 156 . 1 . 318–22 . 1988 . 3178837 . 10.1016/S0006-291X(88)80842-8 . etal.
• Shen WF, Fletcher TS, Largman C . Primary structure of human pancreatic protease E determined by sequence analysis of the cloned mRNA. . Biochemistry . 26 . 12 . 3447–52 . 1987 . 3477287 . 10.1021/bi00386a030 .
• Strausberg RL, Feingold EA, Grouse LH . Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences. . Proc. Natl. Acad. Sci. U.S.A. . 99 . 26 . 16899–903 . 2003 . 12477932 . 10.1073/pnas.242603899 . 139241. 2002PNAS...9916899M . etal. free .
• Ota T, Suzuki Y, Nishikawa T . Complete sequencing and characterization of 21,243 full-length human cDNAs. . Nat. Genet. . 36 . 1 . 40–5 . 2004 . 14702039 . 10.1038/ng1285 . etal. free .
• Gerhard DS, Wagner L, Feingold EA . The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). . Genome Res. . 14 . 10B . 2121–7 . 2004 . 15489334 . 10.1101/gr.2596504 . 528928. etal.
• Gregory SG, Barlow KF, McLay KE . The DNA sequence and biological annotation of human chromosome 1. . Nature . 441 . 7091 . 315–21 . 2006 . 16710414 . 10.1038/nature04727 . 2006Natur.441..315G . etal. free .

Notes and References

1. Tani T, Ohsumi J, Mita K, Takiguchi Y . Identification of a novel class of elastase isozyme, human pancreatic elastase III, by cDNA and genomic gene cloning . J Biol Chem . 263 . 3 . 1231–9 . Feb 1988 . 10.1016/S0021-9258(19)57291-X . 2826474 . free .
2. Shirasu Y, Takemura K, Yoshida H, Sato Y, Iijima H, Shimada Y, Mikayama T, Ozawa T, Ikeda N, Ishida A . Molecular cloning of complementary DNA encoding one of the human pancreatic protease E isozymes . J Biochem . 104 . 2 . 259–64 . Dec 1988 . 10.1093/oxfordjournals.jbchem.a122454 . 2460440 . etal. free .
3. Web site: Entrez Gene: ELA3B elastase 3B, pancreatic.
4. Web site: Entrez Gene: chymotrypsin-like elastase family, member 1 .
5. Molinari I. . September 2004. Fecal chymotrypsin and elastase-1 determination on one single stool collected at random: diagnostic value for exocrine pancreatic status . Clin Biochem . 37 . 9. 758–763 . 15329313 . 10.1016/j.clinbiochem.2004.03.010 . etal.
6. Fecal Elastase 1 ELISA For Exocrine Pancreatic Insufficiency: Comparison With ERCP-Morphology And Fecal Fat Excretion http://www.uniklinikum-giessen.de/med3/poster/publ_pdf/118.pdf