title: Characterization of an Equine α-S2-Casein Variant Due to a 1.3 kb Deletion Spanning Two Coding Exons.
abstract: The production and consumption of mare's milk in Europe has gained importance, mainly based on positive health effects and a lower allergenic potential as compared to cows' milk. The allergenicity of milk is to a certain extent affected by different genetic variants. In classical dairy species, much research has been conducted into the genetic variability of milk proteins, but the knowledge in horses is scarce. Here, we characterize two major forms of equine αS2-casein arising from genomic 1.3 kb in-frame deletion involving two coding exons, one of which represents an equid specific duplication. Findings at the DNA-level have been verified by cDNA sequencing from horse milk of mares with different genotypes. At the protein-level, we were able to show by SDS-page and in-gel digestion with subsequent LC-MS analysis that both proteins are actually expressed. The comparison with published sequences of other equids revealed that the deletion has probably occurred before the ancestor of present-day asses and zebras diverged from the horse lineage.
authors.affiliation: Institute of Animal Breeding and Husbandry, Christian-Albrechts-Universität Kiel, Kiel, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Brinkmann
authors.affiliation: Systematic Proteomics & Bioanalytics, Institute for Experimental Medicine, Christian-Albrechts-Universität Kiel, Kiel, Germany.
authors.forename: Tomas
authors.initials: T
authors.lastname: Koudelka
authors.affiliation: Institute of Human Nutrition and Food Science, Division of Food Technology, Christian-Albrechts-Universität Kiel, Kiel, Germany.
authors.forename: Julia K
authors.initials: JK
authors.lastname: Keppler
authors.affiliation: Systematic Proteomics & Bioanalytics, Institute for Experimental Medicine, Christian-Albrechts-Universität Kiel, Kiel, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Tholey
authors.affiliation: Institute of Human Nutrition and Food Science, Division of Food Technology, Christian-Albrechts-Universität Kiel, Kiel, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Schwarz
authors.affiliation: Institute of Animal Breeding and Husbandry, Christian-Albrechts-Universität Kiel, Kiel, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Thaller
authors.affiliation: Institute of Animal Breeding and Husbandry, Christian-Albrechts-Universität Kiel, Kiel, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Tetens
mesh_terms: D000485:Allergens / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D002364:Caseins / Q000235:genetics*; D004247:DNA / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004063:Digestion / Q000235:genetics; D005060:Europe; D005091:Exons / Q000235:genetics*; D005260:Female; D014644:Genetic Variation / Q000235:genetics*; D006736:Horses; D013058:Mass Spectrometry; D008892:Milk / Q000378:metabolism; D008894:Milk Proteins / Q000235:genetics; D016364:Reading Frames / Q000235:genetics; D017384:Sequence Deletion / Q000235:genetics*
chemical_list: D000485:Allergens; D002364:Caseins; D018076:DNA, Complementary; D008894:Milk Proteins; D004247:DNA