Characterization of a new allele encoding αs2−casein in the Lacaune dairy sheep: possible phylogeny relationship among CSN1S2 alleles

Abstract Text: A new genetic variant of ovine α_S2-casein (named α_s2-CN*H) was identified at the protein level and further characterized at the genome level. The molecular mass of the 12-phosphate α_s2-CN*H isoform was measured as 25,586.984 Da by electrospray ionization mass spectrometry (ESI-MS). Compared with variant A, two nucleotide substitutions were found in exon 11 (A65G) and exon 15 (G64A) leading to the amino acid substitutions: I105V and R161H, respectively. The comparative analysis of nucleotide sequences for alleles present in the Lacaune dairy breed suggests an evolutionary relatedness between CSN1S2*D and H allele. Hence, a possible phylogeny relationship is proposed for CSN1S2alleles in sheep.

Keywords: ovine α_s2-casein, genetic polymorphism, nucleotide sequence