Milk Proteins: Inter-Species Comparison of Milk Proteins: Quantitative Variability and Molecular Diversity

Abstract

In the last few years, developments in molecular biology, genomics, and proteomics have allowed remarkable progress in the understanding of milk protein structure and function, highlighting the extreme complexity and large variability (qualitative and quantitative) of the milk protein fraction, across, but also within, species. Meaningful examples taken in different species, including non-eutherian mammals, are discussed in this article to show how genomes and genetic polymorphisms may modulate the milk protein fraction by affecting different cellular processes, mainly at the posttranscriptional level (splicing of primary transcripts, posttranslational modifications), making milk a more complex biological fluid than previously assumed. However, the repertoire of minor milk proteins remains to be characterized in most species. Numerous substantiated or potential bioactive protein components have been found and many others still remain to be identified either as intact protein or as derived peptides, encrypted in the sequence of milk proteins. This is probably one of the greatest challenges facing milk science in the next years to provide the food industry and consumers with the basis for health-promoting properties of these proteins and peptides.