Characterization of equine cDNA sequences for αS1-, β- and κ-casein
- 17 February 2003
- journal article
- research article
- Published by Cambridge University Press (CUP) in Journal of Dairy Research
- Vol. 70 (1) , 29-36
- https://doi.org/10.1017/s002202990200599x
Abstract
Here we report the entire cDNA sequences for equine αS1-, β- and κ-casein. Based on interspecies comparison, nine exons were found in equine β-casein and five in κ-casein. In equine αS1-casein cDNA the exon 5 was missing, which resulted in the total of 18 exons instead of 19 theoretically possible exons in αS1-casein cDNA. Comparison of DNA sequences representing exon 5 in other species with corresponding equine genomic region confirmed the presence of cryptic exon in horse genomic DNA. Equine αS1-casein mRNA was present in three forms in the lactating mammary gland and we showed that the two shorter forms were produced by skipping either the exon 8 or exon 15. In horse, as in some other mammals, β- and κ-casein are considerably more conserved (sequence identity 53% to 59% and 57% to 67%, respectively) than αS1-casein which appears as the most variable casein among species (sequence identity 40% to 54%). Interestingly, horse caseins resemble human much more than bovine caseins which may also explain the high dietetic value of mares' milk.Keywords
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