Proteomic Analysis of Cow, Yak, Buffalo, Goat and Camel Milk Whey Proteins: Quantitative Differential Expression Patterns

To aid in unraveling diverse genetic
and biological unknowns, a
proteomic approach was used to analyze the whey proteome in cow, yak,
buffalo, goat, and camel milk based on the isobaric tag for relative
and absolute quantification (iTRAQ) techniques. This analysis is the
first to produce proteomic data for the milk from the above-mentioned
animal species: 211 proteins have been identified and 113 proteins
have been categorized according to molecular function, cellular components,
and biological processes based on gene ontology annotation. The results
of principal component analysis showed significant differences in
proteomic patterns among goat, camel, cow, buffalo, and yak milk.
Furthermore, 177 differentially expressed proteins were submitted
to advanced hierarchical clustering. The resulting clustering pattern
included three major sample clusters: (1) cow, buffalo, and yak milk;
(2) goat, cow, buffalo, and yak milk; and (3) camel milk. Certain
proteins were chosen as characterization traits for a given species:
whey acidic protein and quinone oxidoreductase for camel milk, biglycan
for goat milk, uncharacterized protein (Accession Number: F1MK50) for yak
milk, clusterin for buffalo milk, and primary amine oxidase for cow
milk. These results help reveal the quantitative milk whey proteome
pattern for analyzed species. This provides information for evaluating
adulteration of specific specie milk and may provide potential directions
for application of specific milk protein production based on physiological
differences among animal species.