alphacaseins

Alphacaseins are a group of proteins within the milk protein family known as alpha-caseins. In many mammals, the major alphacaseins are alpha-s1-casein and alpha-s2-casein. They are encoded by gene loci such as CSN1S1 and CSN1S2 and are produced by mammary epithelial cells before being secreted into milk. Along with beta- and kappa-caseins, alphacaseins comprise the casein fraction of milk and contribute to its nutritional value, emulsification properties, and milk-processing characteristics.

Biochemically, alphacaseins are phosphoproteins rich in serine residues, and they readily assemble into casein micelles that incorporate calcium phosphate. The phosphorylation pattern and the molecular variants of alphacaseins influence micelle stability, calcium binding, and the rate of coagulation during cheese making. Differences in alphacasein genes and expression can affect milk viscosity, gel strength, and cheese yield.

In dairy science and animal breeding, alphacaseins are a focus of genetic and quality research. Polymorphisms in CSN1S1 and CSN1S2 are associated with variation in milk composition and processing traits among cattle and other dairy species. Understanding alphacaseins helps optimize milk for cheese production and other dairy products, and informs discussions about nutrition and dairy genetics.