Part:BBa_K2924028

β-casein

The milk protein β-casein from Bos taurus

Usage and Biology

β-casein (CSN2), also named CASB_BOVIN¹is a gene coding for a protein product, has the GeneID: 281099, which originates from <Bos taurus>².

Caseins are among the most abundant proteins in native cow's milk. They are phosphoproteins and make up approximately 80% of total dairy protein mass. The milk proteins and their proportions are important to the parameters of milk manufacturing and the quality of milk protein. In general casein is anti-catabolic, reduces muscle breakdown and contains high amounts of calcium. Casein has a number of bioactive peptides that can benefit an individual digestive system and immune system. The said peptides can also help the body combat heart disease and heart problems by regulating inflammation and increasing blood clot forming. This is because the above-mentioned peptides have comparable medicinal effects to that of ACE inhibitors or angiotensin-converting enzyme that can help the body manage and control high blood pressure. Bovine β-casein is usually present as a single form with five phosphates. The calcium-insoluble protein also has a highly charged N-terminal region and a hydrophobic C-terminal region^3,4. Just like ɑ-s1-casein, it does not have any cysteine residues⁴.

The DNA sequence of the gene was acquired by reverse-translating the amino acid sequence. Further, in order to reach optimal heterologous expression in Escherichia coli the DNA sequence was designed with optimized codons and synthesized commercially.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  INCOMPATIBLE WITH RFC[21]

  Illegal BamHI site found at 673
  
• 23
  COMPATIBLE WITH RFC[23]
• 25
  INCOMPATIBLE WITH RFC[25]

  Illegal AgeI site found at 630
  
• 1000
  COMPATIBLE WITH RFC[1000]

MIT_MAHE 2020

Summary

∼30% of the total protein contained in bovine milk is made up by β-casein. It has two major genetic types: A1 and A2. A1 and A2 has different effects on gastro-intestinal tract. Many studies and rodent models link consumption of A1 to the initiation of inflammatory response markers plus enhanced Toll-like receptor expression relative to both A2 and nonmilk controls.

References

[1]: https://www.uniprot.org/uniprot/P02666

[2:] https://www.ncbi.nlm.nih.gov/gene/?term=P02666

[3]: Kumosinski, Thomas F., and Harold M. Farrell. "Calcium-induced associations of the caseins: thermodynamic linkage of calcium binding to colloidal stability of casein micelles." Journal of protein chemistry 10.1 (1991): 3-16.

[4]: Fang, Yuan, and Douglas G. Dalgleish. "DEPARTMENT OF FOOD SCIENCE, UNIVERSITY OF GUELPH, GUELPH, ONTARIO NIG 2W1, CANADA." Food Macromolecules and Colloids 156 (1995): 146

[5] Brooke-Taylor, S., Dwyer, K., Woodford, K., & Kost, N. (2017). Systematic Review of the Gastrointestinal Effects of A1 Compared with A2 β-Casein. Advances in nutrition (Bethesda, Md.), 8(5), 739–748. https://doi.org/10.3945/an.116.013953

[6] Kamiński, S., Cieslińska, A., & Kostyra, E. (2007). Polymorphism of bovine beta-casein and its potential effect on human health. Journal of applied genetics, 48(3), 189–198. https://doi.org/10.1007/BF03195213