Characterization of equine cDNA sequences for alphaS1-, beta- and kappa-casein.
Here we report the entire cDNA sequences for equine alphaS1-, beta- and kappa-casein. Based on interspecies comparison, nine exons were found in equine beta-casein and five in kappa-casein. In equine alphaS1-casein cDNA the exon 5 was missing, which resulted in the total of 18 exons instead of 19 theoretically possible exons in alphaS1-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 alphaS1-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, beta- and kappa-casein are considerably more conserved (sequence identity 53% to 59% and 57% to 67%, respectively) than alphaS1-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.
Lenasi
Tina
T
Department of Animal Science, Biotechnical Faculty, University of Ljubljana, Groblje 3, SI-1230 Domzale, Slovenia.
Rogelj
Irena
I
Dovc
Peter
P
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002364:Caseins / Q000737:chemistry / Q000235:genetics*; D018076:DNA, Complementary / Q000737:chemistry*; D005091:Exons; D006736:Horses / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D017385:Sequence Homology
D002364:Caseins; D018076:DNA, Complementary