Characterization of equine cDNA sequences for αS1-, β- and κ-casein

• Published in: Journal of dairy research Vol. 70; no. 1; pp. 29 - 36
• Main Authors: Lenasi, Tina, Rogelj, Irena, Dovc, Peter
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.02.2003
• Subjects: Animal productions; Biological and medical sciences; caseins; cryptic exon; Equus caballus; exon skipping; Fundamental and applied biological sciences. Psychology; Genetic code; Molecular and cellular biology; Molecular genetics; sequence identity; Terrestrial animal productions; Vertebrates; Equus caballus; cryptic exon; exon skipping; caseins; sequence identity; Genome organization; Farming animal; Nucleotide sequence; Nutritive value; Mare milk; Species specificity; Experimental study; Milk protein; Vertebrata; Mammalia; Exon; Messenger RNA; Casein; DNA; Horse; Genetics; Perissodactyla; Animal production; Molecular biology; Ungulata
• ISSN: 0022-0299; 1469-7629
• DOI: 10.1017/S002202990200599X

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.