Chapter 5 - Post-translational Modifications of Caseins

Abstract

The caseins exhibit a high degree of heterogeneity as a result of post-translational modifications (PTMs). Phosphorylation of the αs1-, αs2, and β-caseins and glycosylation of κ-casein are the best known modifications and are critical for the formation and stability of casein micelles. κ-Casein, in particular, has long been known to exhibit a high degree of variability in glycosylation, specifically in the caseinomacropeptide region, which is responsible for stabilization of the micelle. It is somewhat surprising to see so much variability in such important structural features. In recent years, the adoption of proteomic techniques has greatly enhanced our ability to unravel heterogeneity in proteins arising from complex and variable patterns of PTMs. In this chapter, a summary of our knowledge of the PTMs of caseins is attempted, with a particular emphasis on κ-casein and the implications that variations in PTMs have for dairy processors.